A man suspected of attacking setting off bombs outside the Dallas Police headquarters and spraying the building with gunfire in the early hours of this morning was shot and possibly killed by snipers a few hours later, police said.

Dallas Police Chief David Brown said police snipers shot the suspect through the windshield of a van in the parking lot of a fast food restaurant about 10 miles (16 km) south of the city. A robot would be deployed to check the van for explosives before officers go to see whether the man is dead, he said.

In a Twitter feed, police said the suspect was believed to have been killed.

"There has been no contact with the suspect in over 4 hours - believe it likely that he is deceased," the police said in a tweet.

"We've opened the windshield and will utilize an explosive 'water charge' to render any explosives inside inert," the police said in a separate posting on Twitter.

They said they would not go into the vehicle until they were sure there were no explosive devices rigged to it. Small explosions were heard near the vehicle, likely set off by police trying to gain entry, media at the scene reported.

The suspect appeared to be a man who had blamed authorities for losing custody of his son, who is now in middle school, the Dallas Morning News reported.

Dallas resident Ben Sotheby, 56, watched from behind the barricades as police patrolled the area near headquarters.

"It wasn't real smart to shoot up the place where all the cops are at. You'll get yourself killed that way," he said.

No one else was believed to have been hurt in the attack which happened at around 12:30 a.m. (0630 GMT) after police responded to reports of automatic gunfire from what was described as an armored van outside their headquarters.

Initial eyewitness reports that up to four assailants were involved proved to be unfounded and police believe there was only one attacker, Brown said. His motive was unclear, but the suspect had earlier threatened to kill police officers, he said.

At the incident unfolded, two devices exploded outside the police headquarters. The first was a pipe bomb that went off when a police robot attempted to move it. A second device, placed under a police vehicle, was detonated by a bomb squad.

When police closed in on the van, it rammed a squad car and gunfire erupted. The van drove off as police returned fire and officers gave chase, Brown said.

The van stopped in the restaurant parking lot in the city of Hutchins, where there was another exchange of gunfire. Police said they surrounded the van and managed to disable it with a high-powered rifle.

Brown said police negotiators had spoken with someone inside the van, who identified himself as James Boulware.

The police chief said they had not yet been able to confirm the identity of the man, but said police had responded previously to three incidents of domestic violence involving a man with that name.