Roundup: Explosion, stabbing, gunshots in U.S. over weekend

Twenty-nine people were injured in an explosion in the Chelsea neighborhood in New York City Saturday evening, and the city mayor said there has so far been no evidence of a terror connection.

"Early indications are that this was an intentional act," New York City Mayor Bill De Blasio said, adding that "there is no specific and credible threat against New York City at this point in time from any terror organization."

Law enforcement sources have reportedly said they found a device that appeared to be pressure cooker near the explosion site.

Also on Saturday night, a man wearing a private security company uniform stabbed eight people at a mall in the northern U.S. state of Minnesota before an off-duty police officer shot him dead.

The stabbings occurred in multiple locations inside the mall, including in the common area and several stores, according to local police.

"All of a sudden I heard pop pop pop, I thought someone tipped over a shelf. All of sudden these people started running. I just saw everybody running our way," Harley Exsted, who was at the scene, told the local newspaper St. Cloud Times.

Seven of the wounded were treated and released while one victim remains hospitalized. None of their injuries are life-threatening, the CNN quoted police chief William B. Anderson as saying.

"The individual we believe to be responsible for the victim's stab wounds is currently deceased inside the mall," police told the CNN.

The two incidents happened just one day after four U.S. police officers and four civilians were shot in separate incidents in Philadelphia, Pennsylvania and Fort Worth, Texas, authorities said.

In the eastern U.S. city of Philadelphia, Sergeant Sylvia Young, 19, was ambushed late Friday night and shot a number of times in her left arm and protective vest, said Philadelphia Police Commissioner Richard Ross.

The suspect later wounded Ed Miller, a former police officer who is now a member of the security force at the University of Pennsylvania, Ross said.

During the police chase, a woman was killed and three other civilians were injured by the suspect, before he was cornered in an alley and fatally shot by the police.

Young and Miller were rushed to hospital and were in stable condition early Saturday, Ross said.

In another incident in Fort Worth, a city located in north central Texas, two police officers were responding to a suicide call at a house Friday night.

When they entered the house, a suspect inside the backyard shed began shooting, local media reported.

One officer was shot several times and in critical condition, while the suspect was later found dead by the police. Endi