At least 6 Philadelphia policemen shot at by gunman

A gunman who wounded six police officers in a shooting incident that triggered a tense, hours-long standoff in the US State of Philadelphia has been taken into custody, police said on Thursday.

The shooting started at 4:30 pm (local time) in the city's Nicetown neighbourhood on Wednesday and was followed by a standoff that lasted nearly eight hours.

"Suspect is in custody. SWAT is still clearing the house," Philadelphia Police Sergeant Eric Gripp tweeted early Thursday.

The gunman opened fire on police as they were serving a drug warrant in the neighbourhood.

Two officers and three others who had been trapped inside the row house were evacuated by a SWAT team a few hours before the standoff ended, Philadelphia Police Commissioner Richard Ross Jr told reporters.

"They were able to use stealth to do it," he said, adding he didn't think the shooter was aware of the rescue mission.

Ross told reporters that he personally tried to talk to the shooter, but he did not respond verbally.

The city's Police Commissioner identified the suspect as Maurice Hill, 36, who has an extensive criminal history, The New York Times reported.

"All six officers who were shot have been released from area hospitals. One Officer is being admitted for injuries sustained in a vehicle crash related to the incident," Gripp said in a tweet.

White House Principal Deputy Press Secretary Hogan Gidley said President Donald Trump was monitoring the situation.

"The president has been briefed on the shooting in Philadelphia and continues to monitor the situation," Gidley said.

The gunman had fired on every officer who had responded, including the commissioner and a SWAT team vehicle, the authorities said.

The incident comes in the wake of two mass shootings within 24 hours in El Paso and Dayton earlier this month in which 30 people were killed and several others injured.