JERSEY CITY, N.J. (CBSNewYork/AP) — Jersey City police have stepped up patrols following two police-involved shootings this week.

Sources told CBS 2 News there are serious threats against Jersey City officers, stemming from gang members who want to retaliate for a shooting at an all-night Walgreens drugstore this past Sunday morning.

A suspect shot and killed police officer Melvin Santiago. The suspect, Lawrence Campbell, 27, was then shot and killed by police.

Campbell ambushed Santiago, 23, when he and his partner responded to a call at a Walgreens on Communipaw Avenue and John F. Kennedy Boulevard at around 4 a.m. Sunday, police said. Campbell shot Santiago with a gun he had snatched from a security guard he assaulted, police said.

Due to the threats, all officers must patrol in pairs and the department has stepped up security for Officer Santiago’s wake and funeral.

Port Authority and New Jersey State Police who work in Jersey City have also warned their officers.

Earlier Tuesday, Jersey City removed a memorial for Campbell in the neighborhood where he lived. The memorial included candles, balloons and empty liquor bottles. A pair of white t-shirts were taped to a red brick wall, with handwritten messages on them including “thug in peace” and “see you on the other side.”

“I don’t think that a few residents are going to express the sentiment of a city like Jersey City, and I’m not going to have it. So we had it taken down last night,” Mayor Steven Fulop told 1010 WINS’ Glenn Schuck. Fulop previously said the memorial showed “ignorance” and was “disgusting.”

The memorial was erected just a block away from the scene of an unrelated police-involved shooting early Tuesday.

In that incident, two emergency services police officers were on patrol when they spotted a 25-year-old man carrying a six-foot long, wooden fence post with a sharpened end, the Hudson County Prosecutor’s Office said.

When police pulled up next to the man and told him to drop the fence post, the man threw it through the passenger window, hitting an officer in the head, authorities said. The man then reached into the police vehicle, grabbed an officer’s rifle and tried to pull it through the window, prosecutors said.

The officer and the suspect struggled over the gun, which then went off. The bullet went through the inside of the passenger side door and hit the man, and an officer also fired at the man when he refused to show his hands, police said. The suspect was hospitalized with non-life-threatening injuries.

“If someone attempts to seriously injure a police officer, they will respond as necessary to end that threat,” Jersey City Public Safety Director James Shea said of the incident. “That is something they are trained to do.”

Santiago’s funeral is scheduled for Friday at St. Aloysius Catholic Church.

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