The death toll in a west Texas shooting rampage has increased to seven as authorities investigate why a man stopped by state troopers for failing to signal a left turn opened fire on them.
He then fled, shooting more than 20 people as he drove before being killed by officers outside a cinema.
Odessa police spokesman Steve LeSueur said at least one of the shooting victims remained in life-threatening condition.
The gunman has been identified as a white male in his 30s but police have not released a name or possible motive.
The shooting began with an interstate traffic stop where gunfire was exchanged with police, setting off a chaotic rampage during which the suspect hijacked a postal service vehicle and fired at random as he drove in the area of Odessa and Midland.
The two cities are in the heart of Texas oil country more than 300 miles west of Dallas.
Police initially reported possible multiple shooters, but Odessa police chief Michael Gerke later said there was only one male suspect in his thirties.
The suspect shot "at innocent civilians all over Odessa", according to a statement from Odessa police which did not name the man or offer a motive.
The terrifying chain of events began when state troopers tried pulling over a gold car on Interstate 20 for failing to signal a left turn, Texas Department of Public Safety spokeswoman Katherine Cesinger said.
Before the vehicle came to a complete stop, the driver "pointed a rifle towards the rear window of his car and fired several shots" towards the patrol car stopping him.
The gunshots struck one of two troopers inside the patrol car, Ms Cesinger said, after which the gunman fled and continued shooting.
Two other police officers were shot before the suspect was killed. The condition of the three law enforcement officers injured was not immediately released.
Mr Gerke said there were at least 21 civilian shooting victims.
He said at least five people died. Mr Gerke did not say whether the gunman was included among the five dead, and it was not clear whether he was including the five among the at least 21 civilian shooting victims.
Shauna Saxton was one of the terrified drivers who said she encountered the gunman during his rampage, during which multiple witnesses described gunfire near shopping plazas and in busy intersections.
Ms Saxton was driving with her husband and grandson in Odessa and had paused at traffic lights when they heard loud pops.
"I looked over my shoulder to the left and the gold car pulled up and the man was there and he had a very large gun and it was pointing at me," she told TV station KOSA.
Ms Saxton said she was trapped because there were two cars in front of her.
"I started honking my horn. I started swerving and we got a little ahead of him and then for whatever reason the cars in front of me kind of parted," she said sobbing.
She said she heard three more shots as she sped away.
Mr Gerke did not go into detail about the chase, but the cinema where the suspect was killed is more than 10 miles from where state troopers originally pulled over the gunman.
The shooting comes just four weeks after a gunman in the Texas border city of El Paso killed 22 people after opening fire at a Walmart.
Texas governor Greg Abbott this week held two meetings with lawmakers about how to prevent more mass shootings in Texas.
The shooting brings the number of mass killings in the US so far this year to 25, matching the number in all of 2018, according to the AP/USA Today/Northeastern University mass murder database.
If it turns out the gunman is not among the five dead, the number of victims for this year has already reached 140, the level of all last year.
Seven people remained in critical condition at one hospital hours after the West Texas shooting, said Russell Tippin, chief executive of Medical Centre Hospital in Odessa.
He said a child under two years of age was transported to another hospital.
Mr Tippin also said one person the hospital had received had died, although it was unclear if that victim was among the five dead that Mr Gerke reported.
He said 13 shooting victims were being treated at the hospital on Saturday.
Vice president Mike Pence said following the shooting that President Donald Trump and his administration "remain absolutely determined" to work with leaders in both parties in Congress to take such steps "so we can address and confront this scourge of mass atrocities in our country".
Mr Pence said Mr Trump had spoken to the attorney general and that the FBI was assisting local law enforcement.
Mr Trump has offered contradictory messages in reacting to recent mass shootings.
Days after the El Paso shooting, he said he was eager to implement "very meaningful background checks" on guns and told reporters there was "tremendous support" for action.
He later backed away, saying the current system of background checks was "very, very strong".
Most recently, Mr Trump has called for greater attention to mental health, saying that new facilities are needed for the mentally ill as a way to reduce mass shootings.
However, some mental health professionals say such thinking is outdated, that linking mental illness to violence is wrong, and that the impact of more treatment would be helpful overall but would have a minor impact on gun violence.