Nine people have been injured in a shooting outside a shopping centre in Houston in the US state of Texas, one of them critically.
The suspect, who was shot dead by police, has not been identified.
Officials said he was a disgruntled lawyer who fired randomly at drivers.
Numerous weapons were found in what is believed to be the suspect's car, Houston's acting police chief said, adding there were no indications of anyone else being involved.
Police say they are also investigating the gunman's apartment and his social media accounts to try and establish a motive.
"The motivation appears to be a lawyer whose relationship with his law firm went bad,"Houston Mayor Sylvester Turner told reporters.
Six victims were taken to hospital, and three were treated at the scene after being shot at while inside their cars, the city's acting Police Chief Martha Montalvo said. One of the victims is in a critical condition.
The attack comes three days after a shooting at a shopping mall in Washington state, in which five people were killed.
The suspected gunman in that attack, Arcan Cetin, 20, was arrested after a large manhunt that lasted nearly 24 hours.
He appeared in court on Monday, charged with five counts of murder. Court documents say he confessed to shooting all five victims with a rifle. Mr Cetin was born in Turkey and is a legal US resident, officials say.
The motive for the shooting is not known but the suspect's family says he has a history of mental problems.