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At least nine people were injured when a gunman wearing an old military uniform and armed with thousands of rounds of ammunition opened fire in Houston on Monday morning, officials said.

Police were also seen removing what appeared to be an item with Swastika on it from the suspect's car.

Houston police examine suspect in mall shooting's car and recover an item with a Nazi swastika on it. NBC News

Police killed the gunman after he began shooting randomly at passersby and "anyone he could set his sights on," Houston Police Capt. Dwayne Ready said at a news conference.

Acting Houston Police Chief Martha Montalvo said the suspect, who was only identified as a man, lived in the neighborhood and was a lawyer who was having “issues with his law firm.”

Police found old Nazi emblems at the suspect's home, though Ready said they were found among other old military items and it was unclear if they played a role in the shooting.

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Ready described the uniform the suspect was wearing on Monday as military green and historical.

A .45 caliber Thompson carbine — also known as a "Tommy Gun" — was found in the suspect's car, Ready said, along with 2,600 rounds of live ammunition. He also had a .45 caliber semi-automatic handgun and a sheathed, "edged weapon" in his possession, Ready said, adding that authorities had found 75 spent shell casings.

Additional weapons were found at the suspect's home, Ready said, though he would not provide additional details.

Police activity near a shopping center in southwest Houston on Monday. KPRC2

Six victims were taken to area hospitals, Montalvo said. By Monday afternoon, two people remained, said Houston Mayor Pro-Tem Ellen Cohen.

One was listed in critical condition, she said, while the other was in serious condition. Both were expected to recover, she said.

More than 15 EMS crews were dispatched about 6:30 a.m. (7:30 a.m. ET) to reports of shots fired near a Petco store in southwest Houston, Fire Department spokesman Jay Evans told NBC News.

Within a few minutes, Ready said, that status had changed to active shooter, and the suspect used a tree for cover during a shootout with responding police officers. Residents at an apartment complex about a block away were instructed to shelter in place some two hours after the initial reports of the shooting.

One resident, Jennifer Molleda, said that after awakening to gunfire and dialing 911, her husband left for work as he usually does. Moments later, she heard his car come to a screeching stop.

"I immediately called him and said, 'Honey...did you see anything — see anybody out in the street?'" Molleda said. "All he was doing was screaming, 'I'm hit. Jen, I'm hit.'"

Another resident said he was on his way to the gym when there was "an explosion inside my car," he said.

There was "glass everywhere," the resident said. "I heard a few pops — maybe two or three — then I just drove away as fast as I could."

The FBI said it was assisting police with the investigation and no additional suspects were being sought, officials said.

“As victims of the Houston shooting fight for their lives this morning, Cecilia and I ask that all Texans join us in keeping them in your thoughts and prayers,” Gov. Greg Abbott said in a statement.

The shooting comes days after five people were killed by a gunman at a Washington state mall. And earlier this month, a 20-year-old man stabbed 10 people at a Minnesota mall before he was fatally shot by an off-duty police officer.