NEW YORK (CBSNewYork) — Police are stepping up patrols following a string of thefts in Central Park over the last month.

“Crime in the park is down 17 percent this year, however, this past month is up substantially,” NYPD Chief of Department Carlos Gomez said Tuesday. “Parkgoers will see a noticeable increase in police presence in the park. It’ll be on all tours; 24 hours a day there will be more officers there.”

Around midnight Monday, police said a group of teenagers attacked a 47-year-old man riding a Citi Bike on East Drive, knocking him off the bike, punching him in the face and fleeing with his iPhone.

Jacob Angstreich said a group of teenagers attacked him near 95th Street. He said one of the suspects stopped him — with his fist.

“He just hit me in the head. Knocked me off the bike. I fell off the bike,” he said.

He had his iPhone stolen during the incident.

“In the interim, my iPhone had fallen out of my pocket into the ground and one of the kids picked it up and grabbed it, and saw it was an iPhone 7 and started waiving it around saying ‘look at what we’ve got, an iPhone 7, I’m going to keep this,” he recalled.

Angstreich was able to call 911 on his other phone, and tried to chase down the suspects, but they were too quick.

He said he plans to return to the park.

“If I had been a little more worried about crime in the park, as soon as I saw those kids I would have just turned around and avoided it,” he said.

In another incident on Friday night, another man said he was followed by eight men, hit in the back of the head, and had his also iPhone stolen.

There have been a total of five cell phone robberies in the past three and a half weeks. Police believe the thefts are connected.

Police are also investigating an unrelated attempted sex assault that occurred around 9:30 p.m. Monday. A 28-year-old woman was jogging on East Drive near 107th Street when sources said a man came up behind her and pulled her into a desolate wooded area, CBS2’s Christine Sloan reported. Sources say she was punched and kicked in the head, then fondled.

The suspect took off with her iPhone, which was later located in the Bronx, Sloan reported.

Police described the suspect in that case as a man in his 30s with a scruffy beard wearing a dark jacket and an orange T-shirt.

That incident is not connected to the other thefts.

While crime is down, there has been a sudden spike in robberies in Central Park in the past 28 days — 5 to 1 during the same time period last year.

“Bad month for the park but we’re deploying a lot of resources into that area so we can stem this and solve these crimes,” Chief of Detectives Bob Boyce said.

Parkgoers are being urged to take precautions.

“We do want people to use our parks but you have to be aware of your surroundings,” NYPD Commissioner James O’Neill said. “If it’s late at night take a partner if you’re going to go running.”

Many are heeding the warning.

“I am not worried during the day, I wouldn’t be here out at nighttime. I wouldn’t recommend that, even if you are training,” Upper West Side resident Diana Calantoni said. “It’s very important when you’re training, I know you got to get out and get your miles in but not at nighttime. If you’re running at night I recommend you stay on the lower loop.”

“You have to stay vigilant and look out for yourself,” Australian resident Michael Doyel said.

So far, none of the suspects have been caught.

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