CBS News: Istanbul Suicide Bombers May Have Been Chechen Jihadists From Russia

ISTANBUL (CBSNewYork/AP) -- It was an attack that echoed the carnage earlier this year at the Brussels airport, down to the taxi that carried the men to their target: Inciting panic and then taking lethal advantage, three suicide attackers unleashed a deadly tide of bullets and bombs at Istanbul's Ataturk Airport, leaving 42 dead.

Authorities blamed the Islamic State of Iraq and Syria for the blood bath late Tuesday, a coordinated assault on one of the world's busiest airports and on a key NATO ally that plays a crucial role in the fight against the extremist group.

There was no immediate claim of responsibility by the terror group.

CBS News correspondent Margaret Brennan reported the current working theory is the attackers may have been Chechen jihadists from southwest Russia who could have links to ISIS.

Chechnya is the same Russian region that produced the Tsarnaev brothers who set off bombs at the Boston Marathon in 2013.

DNA tests on the Istanbul attackers are underway.

More than 230 people were wounded in the attack, but 109 have been discharged from hospitals.

Meanwhile, Turkey's Prime Minister Binali Yildirim told reporters that air traffic returned to normal and "Our airport has been opened to flights and departures'' in a press statement at the airport early Wednesday morning.

Turkish Airlines' website says "flight operations have been restarted'' and instructs passengers to monitor actual flight information.

As CBS2's Tony Aiello reported, there was also frustration and heartbreak at the Istanbul morgue Wednesday, as families ached for news about missing loved ones.

Not far away, one of 19 funerals was held on Wednesday. Men gathered to pray for a 25-year-old airport worker who died in the attack.

At Ataturk Airport, passengers walked past damage from the attack as workers cleaned up and made repairs.

But repairing the Turkish tourism industry will not be so easy. Istanbul's famous Blue Mosque and other sites were far less crowded than usual.

"I feel absolutely terrible this is happening to Turkey," said tourist Wendy Deaton. "Everyone that we've come across here has just been so gentle and nice, and I think it's devastating for the economy and for the tourism here."

A series of attacks over the last year has damaged Turkey's image as a safe haven in a dangerous region. An Internet home for hotel rooms found discounts averaging about 40 percent below normal rates.

Back at the airport, daylight in Istanbul Wednesday revealed more of the devastating aftermath. Workers were seen removing debris from a destroyed terminal where walls of glass were completely blown out from the impact of the blasts.

Dutch businessman Henk de Jager returned to the airport after witnessing the triple suicide bombings.

"I saw one of the suicide killers blow himself up," he said.

In a video posted after Tuesday night's attack, a Turkish fireman walks past the motionless body of a man lying face up, most of his right arm missing, near a Turkcell phone stand. Police and investigators carrying crackling radios examine the scene, where a few dazed passengers remain, weaving their way through scraps of debris littered over a bloodied floor.

Ticket windows were also shattered by bullets from the attackers, who officials say arrived in a taxi before opening fire and setting off explosives.

Surveillance video captured the moment one of the suicide bombers blew up outside the international terminal. Other footage appears to show a second attacker, who falls, drops a weapon and then detonates his vest soon after. The third attacker set off explosives in an airport parking lot.

"There was a constant threat of someone coming around the corner and shooting. They were saying that there were still people in the building with guns," said witness Rihards Kalnins. "A lot of fear -- there were people cowering in the corners."

CBS News further reported investigators have located the taxi driver who dropped the men off, and he said he did not recognize the language the men were speaking.

The triple bombings came only a day after the U.S. re-issued a travel alert, warning about increased terror threats in Turkey.

"It certainly seems to suggest there was additional information available to the US government and certainly to the Turks that there were threats perhaps in the offing and it doesn't suggest that they saw something that was troubling," CBS News' senior security analyst Juan Zarate said.

CBS News' Jonathan Vigliotti reported that security experts said the attackers were targeting the airport's large crowds.

"These individuals were likely not only well-armed, but trained, and certainly had coordinated before the attack and planned it out for a number of weeks, if not months," Zarate said.

Officials say it proves the need for constant vigilance.

"We have to get it right 24-7, 365. They have to get it right for 10 minutes or one hour," U.S. Secretary of State John Kerry said.

Those who survived recounted the frightening moments as scores of people ran, some ducking into stores.

"We had some people, they were so scared," said witness Thomas Kemper. "They started to try to get out of the windows from the Turkish Airlines lounge, but, of course, the glass was too heavy."

Recent Fordham graduate Adam Keally was among those who escaped.

"People were shooting on one side and we all ran the other way and then bombs went off," he said.

Sam Spennato was on board one of the last flights out of Istanbul. She's now back home in Atlanta.

"I'm shaking, but I'm relieved," she said. "I just started thanking God that I was in the air and that he was watching over me and I was fine."

While officials say the nature of the attacks leads them to believe ISIS may be behind them, the group has not claimed responsibility, CBS2's Janelle Burrell reported.

Security experts say this latest attack proves ISIS and terror cells are expanding their reach, going after soft targets in Western capitals.

"ISIS is trying to find vulnerabilities, not just to attack in places like Iraq and Syria but well beyond into places Turkey, Europe and even potentially in North America," Zarate said.

White House spokesman Josh Earnest said the United States condemns the attacks in the strongest terms possible.

He said the Istanbul airport, like the Brussels airport that was attacked earlier this year, is a symbol of international connections and the ties that bind nations together.

Earnest said the United States remains steadfast in its support for Turkey, a NATO ally and partner, "along with all of our friends and allies around the world, as we continue to confront the threat of terrorism.''

President Barack Obama also offered his condolences to the Turkish people. He spoke after a one-on-one meeting in Canada with Mexican President Enrique Pena Nieto.

"We have offered all assistance that we have available to our ally, Turkey, and we stand prepared to assist them during this difficult time," Obama said.

Obama also spoke with Turkish President Recep Tayyip Erdogan during the flight to Canada.

Meanwhile, CIA Director John Brennan said ISIS is determined to carry out attacks beyond the Middle East. He said he would be surprised if the terror group did not try an Istanbul-style attack in the U.S., making security measures and intelligence gathering all the more critical.

Airports around the world have increased their security in response to the attack.

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