A man barricaded himself in a house after telling police he had killed three relatives, then opened fire on a SWAT team Thursday, killing one officer and wounding another, police said. Ten hours after he initially called police, the house was on fire.

After the man and police exchanged gunfire just after midnight, he apparently remained in the house, which was on fire around 7:30 a.m Thursday.

Flames shot out of the windows and smoke was coming out on several sides of the house. Firefighters sprayed the house with water, but did not go into the home. It was unclear how the fire started, although tear gas had been used.

The standoff began at 9 p.m. Wednesday and continued into Thursday morning. The home was surrounded by more than 200 officers.

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The two officers were shot inside the home shortly after they arrived, Assistant Chief Jim McDonnell said at a news conference. Authorities had not been able to determine whether the man had killed his family members.

Shortly before 6 a.m., police lobbed tear gas into the home. Wind blew the gas back toward some officers, who retreated from the cloud. Police could be seen in footage from a television helicopter using a battering ram to break into the home.

Several blocks of the San Fernando Valley neighborhood were sealed off with yellow crime tape. A police helicopter circled overhead, its searchlight on.

Both officers were taken to Northridge Medical Center, where one of them, 51-year-Randal Simmons, died just after 1 a.m., McDonnell said. The other, 51-year-old James Veenstra, was undergoing surgery, and was expected to survive, McDonnell said.

Mayor Antonio Villaraigosa said he had visited with the family of the slain officer. Simmons leaves a wife and two children. Veenstra's wife is a captain on the force.

"This is a very horrible tragedy and our hearts go out to all the members of the LAPD who also are grieving at this time," Villaraigosa said.

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The Associated Press contributed to this story.