By Terry Wade

HOUSTON (Reuters) - A Houston lawyer whose business was struggling opened fire on morning commuters on Monday, injuring at least nine people before being shot dead by police, authorities said.

Six people were taken to hospitals and three were treated at the scene after being shot at while inside their vehicles in the affluent neighborhood of West University Place, acting Houston Police Chief Martha Montalvo told reporters.

One victim was in critical condition and another was in serious condition but both were expected to survive, officials said. The Federal Bureau of Investigation said there was no indication that the shootings were linked to a radical group.

Police declined to identify the suspect, but local media reported that he shot at vehicles from a black Porsche registered to Nathan DeSai.

Public records showed that DeSai lived in a condominium near the shooting scene and that he had no criminal record.

DeSai, who received his law degree from the University of Tulsa in 1998, started a small law firm but his former law partner, Ken McDaniel, said they closed it about six months ago.

McDaniel told local television the shooting was "out of character" for DeSai.

Houston Mayor Sylvester Turner, in Cuba to develop trade relations, told reporters, "The motivation appears to be a lawyer whose relationship with his law firm went bad."

Prakash DeSai told ABC television's Houston affiliate that his son drove a black Porsche, and that he was "upset about his law practice not going well" and money woes.

Police said the suspect was dressed in a military-style uniform and that military paraphernalia that included Nazi items was found in his possession.

The police bomb squad secured the shooter's car, which contained more than 2,600 rounds of ammunition. Police said a handgun was found on the suspect's body and a rifle was found in this car.

An agent for the Bureau of Alcohol, Tobacco, Firearms and Explosives said the firearms had been legally purchased.

Christopher Miller, who lives near the site of the shootings, said he watched much of it from his apartment. “The only way I can explain it is like a firework show; you hear a shot, a shot, then more shots, then a finale of a bunch of shots. Then you know it’s over.”

Police said more than 75 shell casings had been recovered.

(Additional reporting by Ruthy Munoz in Washington, D.C., Jon Herskovitz in Austin, Texas,; Laila Kearney in New York and Sarah Marsh in Havana; Editing by Bernadette Baum and Bill Trott)