Six Philadelphia police officers were shot and wounded on Wednesday in a shootout during a drug raid on a house and negotiators were urging the shooter to surrender as two officers remained trapped inside the home, police said.

Over four hours into the standoff, the Philadelphia Police Department (PPD) said all of the wounded officers were in stable condition with non-life-threatening injuries.

Police were serving a drugs warrant inside a north Philadelphia home at around 4:30 p.m. when the male shooter opened fire on officers.

"Many of them had to escape through windows and doors to escape from a barrage of bullets," Philadelphia Police Commissioner Richard Ross told a news conference.

The shooter continued to fire on a SWAT truck parked outside the residence in the Nicetown-Tioga neighborhood, with rounds hitting a building across the street, as officers tried to negotiate his surrender, Ross said.

"The suspect remains barricaded as PPD Officers continue to attempt to communicate with him," Police spokesman Eric Gripp tweeted at around 9 p.m.

Police called the man's phone, talked with him on a bullhorn and involved a family member in the negotiations, Ross added.

"I'm worried about a potential hostage situation and we've got to get that resolved," said Ross, adding that he believed the two officers trapped inside the home were not wounded.

"We are trying to get him to come out peacefully," Ross said. "There's no indication that he's trying to surrender, we do know that he is still alive, there's no question of that because of the shots that keep ringing out."

Ross said the officers inside the home may be holding people they arrested during the raid. Local media reported the trapped officers were holding around three suspects.

Police told local residents to remain inside their homes and stay out of the area after hundreds of rounds were exchanged.

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Local television station Fox 29 reported some kind of movement by police around 7:30 p.m. when a large bang was heard.

Two other officers were also injured in a car accident while responding to the shooting.

There were reports the shooter was livestreaming the incident on Facebook.

President Donald Trump has been briefed on the shooting and was monitoring the situation, the White House said.

Local media reported the shooter appeared to have a high-powered weapon and a significant amount of ammunition. The incident follows a string of mass shootings in California, Texas and Ohio in which gunmen used semi-automatic rifles.

"I'm a little bit angry about someone having all that weaponry and all that firepower, but we'll get to that another day," said Mayor Jim Kenney after visiting three of the wounded officers in hospital.