(CNN) -- A man thought to be a serving British soldier was killed by two armed men in a frenzied attack on a London street Wednesday, in what the government is treating as a suspected act of terrorism.
Witnesses told of a gruesome scene in which the man was hit by a car, then hacked with cleavers and his body dumped in the middle of the road.
The two suspects in the killing were injured in a confrontation with police and have been taken to two hospitals, where they are being treated.
CNN affiliate ITN aired a video showing a man holding a meat cleaver and saying, "we swear by almighty Allah we will never stop fighting you."
The government is treating the gruesome killing as a suspected terrorist attack, Prime Minister David Cameron's office said.
Cameron described the killing as "truly shocking" on Twitter.
He has called a meeting of the country's civil emergency committee, known as COBRA, to discuss authorities' response.
The man is believed to be a serving soldier who was based at a nearby barracks, Nick Raynsford, a member of Parliament, told CNN.
The soldier had apparently been on duty in central London and was returning to the Royal Artillery Barracks in Woolwich when he was attacked, Raynsford said.
London Mayor Boris Johnson tweeted: "This afternoon's attack in Woolwich is a sickening deluded and unforgivable act of violence. My thoughts are with the victim and his family."
It's not yet known what the motivation is for the attack.
UK Home Secretary Theresa May described it as a "a sickening and barbaric attack."
Commander Simon Letchworth told reporters in Woolwich that local officers had responded when an assault was reported at 2:20 p.m. Wednesday and a firearms unit was called to the scene. British police do not usually carry firearms.
"Two men, who we believe from early reports to have been carrying weapons, were shot by police," he said. "They have both been taken to separate London hospitals and are receiving treatment for their injuries."
'They were hacking at this poor guy'
Eyewitnesses have given gruesome details of the killing.
One, Michael Atlee told CNN he and friends heard gunshots and when they turned the corner saw a pool of blood on the sidewalk and a trail of blood leading into the road.
The man killed appeared to be wearing a T-shirt for Help for Heroes, a charity that helps military veterans, he said.
Another witness, who gave his name only as James, told London's LBC 97.3 radio station that he saw two men standing by the victim on the floor.
At first he thought they were trying to help the man but then saw two meat cleavers, like a butcher would have.
"They were hacking at this poor guy, literally," he told the radio station, as if they were trying to remove his organs.
"These two guys were crazed. They were just not there. They were just animals."
The men appeared to want to be filmed, he said, saying that one of the attackers went over to a bus and asked people to take photos of him as if he wanted to be on TV.
He said the two men had rushed at the police when they arrived, at which point shots were fired and both men went down.
Lauren Collins told CNN: "I still am quite shaken at what I've seen -- I've seen a victim of an awful attack, and I've seen a body of a young man."
Another witness, Woolwich Theatre owner Adrian Green, said the incident was "shocking" but did not reflect the true nature of the area.
Raynsford said the military based at the centuries-old barracks had a close relationship with the local community. Woolwich is a mixed, multicultural area, he added.