A man suspected of carrying out a terrifying targeted attack of police headquarters in Dallas, Texas, has been shot dead by snipers after a tense stand-off.

The suspect had allegedly planted several bombs and sprayed the headquarters and squad cars with gunfire during the assault in the sprawling city. No one else was killed, and police ruled out any connection to terrorism.

The night of violence began around 12:30 am local time (3:30pm AEST yesterday), when a man in an armored van rammed into police squad cars at the headquarters and the suspect opened fire.

Shots rang out from several different locations, leading police initially to believe multiple gunmen were involved, before they established the attacker was acting alone.

The suspect is believed to be James "Jimmy" Boulware. (Dallas PD)

The site of the detonated pipe bombs. (AAP)

"We're blessed that our officers survived this ordeal," Dallas Police Chief David Brown said.

"There are bullet holes in squad cars where officers were sitting. There are bullet holes in the front lobby where staff was sitting."

He described how the suspect had fired multiple shots at the police headquarters, pausing to reload and apparently using an assault rifle and a shotgun.

The suspect "meant to kill officers and took time to discharge that weapon multiple times to accomplish their wanting to harm our officers," Mr Brown added.

Shortly after, police chased the van to Hutchins, a nearby suburb south of the city, where officers surrounded the vehicle and more shots were traded. Several bullets hit police cars but, again, no officers were injured.

Officers tried to negotiate with the suspect, who gave his name as James Boulware, though police were not immediately able to confirm his identity.

Brown said there was no connection to terrorism and that the incident stemmed from an issue surrounding custody of the suspect's child.

A man claiming to be the suspect's father, Jimmy Lee Boulware, said his son felt "beaten down" by police and Child Protective Services over a custody battle with his son.

The elder Mr Boulware, 73, also told CBS affiliate KTVT that James struggled to find and keep a good paying job due to his past criminal record.

Police have not yet provided a possible motive for the attack.

"He doesn't show to be in our databases on any terrorism watchlist or anything like that," Brown said. "So it may have just been a rant."

The Dallas Police Association, which represents Dallas officers, tweeted that the suspect had "three family violence cases against him. (He) was very disgruntled against law enforcement and the criminal justice system."

Officers had to dodge gunfire during the attack. (AAP)

Texan police surround the gunman's vehicle. (Supplied, Twitter)

At 4:40 am (7:40pm AEST), police sent in an explosives robot to examine a bag that had been found back at the police headquarters. The bag blew up as the robot tried to move it, damaging several cars.

Brown earlier said other pipe bombs had been found in one of four duffle bags that were "dispersed throughout the front and side of police headquarters."

Around the same time, following attempts to negotiate with the suspect, snipers used a powerful .50-caliber rifle to disable the van's engine block, then they shot the suspect about half an hour later.

Officers from the Dallas Police Department's specialized SWAT unit fired through the front windshield of the armored van, Mr Brown said.

Police sent in a bomb disposal robot to examine the vehicle and determine whether the suspect was dead. They also planned on carried out a controlled blast to render any explosives in the van inert.

The shattered front of the Dallas PD building. (Dallas PD)

"We can now confirm that the susp in the van is deceased but unable to confirm ID pending Med Ex. identification," the Dallas Police Department tweeted, using an abbreviation for medical examiner, or coroner.

Police ramped up security at other law enforcement facilities in Dallas as a precautionary measure after the attack.

In November, police shot and killed a man in the Texas state capital Austin after he opened fire at several buildings including the police headquarters.