Updated at 10 a.m. Sept. 1: Revised to include an updated death toll.

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At least seven people died after more than 20 people were shot Saturday when a gunman hijacked a postal truck and began shooting randomly in the Odessa area of West Texas, authorities say.

At least three law enforcement officers — a state trooper, an Odessa police officer and a Midland police officer — were among those shot. They were in stable condition Saturday night, according to the Texas Department of Public Safety.

Read more: Death toll rises to 8 after gunman shoots more than 20 in West Texas rampage, Odessa police say

Odessa Police Chief Michael Gerke confirmed that authorities had fatally shot the gunman, whose name has not been released.

Gerke said at least 21 people had been shot. He did not indicate whether he was including the gunman in the death toll. It was unclear whether the number of people who were shot included the dead or whether the number was a count of the wounded.

The shooting began after 3 p.m., when a Department of Public Safety trooper tried to stop a Honda on Interstate 20 for failing to signal a left turn. The driver shot one of two troopers in the patrol car, and the gunman continued driving west into Odessa and shot another victim on the highway, police said.

At some point in Odessa, the gunman abandoned the Honda, hijacked the postal truck and shot more people, Gerke said.

The gunman traveled along I-20 and State Highway 191, which connect Odessa and Midland. Law enforcement personnel fatally shot him after he drove east to a Cinergy movie theater in Odessa. Cellphone video showed people running out of the theater.

Police tape hangs at a Cinergy movie theatre Saturday, Aug. 31, 2019 in Odessa, Texas. At least five people died after more than 20 people were shot Saturday when a gunman hijacked a postal truck and began shooting randomly in the Odessa area of West Texas, authorities say. (Ryan Michalesko / Staff Photographer)

A video labeled "Dios mío por favor protegenos" ("My God, please protect us") posted under the name Antonio Orozco Garcia on Facebook showed people frantically taking cover on the ground some distance outside what appeared to be the theater.

While what sound like gunshots are heard in the distance, a man in the video yells "Get down! Get down!" at those around him and adults hold screaming children tightly to their bodies. A boy is heard asking "Who's shooting? Who's shooting, Dad?"

Although the gunman's name had not been released, Gerke said he had some idea of who the man was and described him as white and in his 30s.

A 17-month-old who was shot in the face was among the victims, KWES-TV reported. The child, whose condition was unknown, was airlifted to University Medical Center in Lubbock.

1 / 3A crashed U.S. Postal Service vehicle, left, and Odessa Police vehicle are seen Sept. 1, 2019 at a Cinergy movie theatre in Odessa, Texas where police took down a gunman Saturday. At least five people died after more than 20 people were shot Saturday when a gunman hijacked a postal truck and began shooting randomly in the Odessa area of West Texas, authorities say.(Ryan Michalesko / Staff Photographer) 2 / 3A Cinergy movie theatre where police took down a gunman on Saturday is seen Sunday Sept. 1, 2019 in Odessa, Texas. At least five people died after more than 20 people were shot Saturday when a gunman hijacked a postal truck and began shooting randomly in the Odessa area of West Texas, authorities say.(Ryan Michalesko / Staff Photographer) 3 / 3Media and law enforcement are seen Sunday, Sept. 1, 2019 at a Cinergy movie theatre in Odessa, Texas where police took down a gunman Saturday. At least five people died after more than 20 people were shot Saturday when a gunman hijacked a postal truck and began shooting randomly in the Odessa area of West Texas, authorities say.(Ryan Michalesko / Staff Photographer)

Russell Tippin, CEO of Medical Center Hospital in Odessa, said 13 victims were being treated there, but he did not provide details about their conditions or other information about the victims. He earlier said 14 victims had been taken to the hospital.

Police initially believed that there could be more than one gunman, but Gerke said authorities now believe there was only one.

"Once this individual was taken out of the picture, there have been no more victims," he said.

Dustin Fawcett said he was sitting in his truck at a Starbucks in Odessa when he heard at least six gunshots ring out less than 50 yards behind him.

Fawcett, an Odessa transportation consultant, "got out to make sure everyone was safe." He said a little girl was bleeding and found out she had been grazed on the face.

He said that when police pulled out their rifles and vests, he realized "this is not a drive-by. This is something else, this is something bigger," Fawcett said.

Police are seen Saturday, Aug. 31, 2019 at a Cinergy movie theatre in Odessa, Texas. At least five people died after more than 20 people were shot Saturday when a gunman hijacked a postal truck and began shooting randomly in the Odessa area of West Texas, authorities say. (Ryan Michalesko / Staff Photographer)

Saturday's shootings occurred only four weeks after a gunman killed 22 people in El Paso, about 280 miles away, and one day before several laws took effect in Texas to loosen restrictions on guns, including allowing firearms in public places like churches and schools.

Read more: What are the gun laws in Texas, and what's changing Sept. 1?

Jessica Diaz, 27, a private nurse, was driving with her husband Saturday when alerts from friends on social media began to come in on her phone, warning her to stay off the road.

She went straight home, with memories of the El Paso massacre that targeted Hispanics adding to her fears. Like many in the Midland and Odessa area, Diaz has family and friends in El Paso.

"I'm not going to lie, but that went through my mind: Is this shooter, or shooters, targeting Hispanics?" she said. "You don't know whether he was aiming for us. That's more worrisome because there are so many here. Either way it was nerve-racking, overwhelming. You don't want anyone, regardless of race, to be a victim of a crazy person."

Yolanda Navarro, 49, said she and her husband, with her daughter driving behind them, sensed that something was wrong as an array of police cars passed them.

"We got home and heard the news, and we immediately locked ourselves inside. We've been told to stay inside our house. Everyone is tense. ... We're desperate, unsure what to do. This is Labor Day weekend. We were looking forward to a relaxing weekend with family."

Ector County ISD, a school district in Odessa, said in a statement that its staff were "heartbroken and outraged by the violence that struck our community and our school district" Saturday.

"We are learning that we have lost friends, family members, and one of our students," the district said in the statement. "Our lives have been changed forever."

The district did not provide further details about the student victim, but thanked first responders who "prevented an even greater loss of life."

Counselors at the district and across the region were preparing to help students, staff and families cope with the tragedy, the district said.

A local funeral home, Perches Funeral Home of Odessa, said in a Facebook post it was offering free services after the shooting.

Gov. Greg Abbott issued a written statement calling Saturday's shooting a "senseless and cowardly attack." He said he would travel to Odessa on Sunday morning.

"The first lady and I are heartbroken ... and we offer our unwavering support to the victims, their families, and all the people of Midland and Odessa. The state of Texas and the Department of Public Safety are working closely with local law enforcement to provide resources as needed and deliver justice for this heinous attack.

"I thank the first responders who have acted swiftly and admirably under pressure, and I want to remind all Texans that we will not allow the Lone Star State to be overrun by hatred and violence. We will unite, as Texans always do, to respond to this tragedy."

President Donald Trump tweeted that he had been briefed on the shooting.

"FBI and Law Enforcement is fully engaged," he wrote.

Texas Attorney General Ken Paxton also said the state's law-enforcement resources would be deployed as needed in the investigation.

"I am horrified to see such a senseless act terrorize the fine people of the Permian Basin," he said in a written statement. "... I have asked my law enforcement division and my crime victims services team to assist in any way necessary."

Texas' U.S. senators also responded with their condolences in written statements.

"Tonight we are one with the entire Midland-Odessa community, especially the victims of this horrific tragedy," Sen. John Cornyn said.

Sen. Ted Cruz expressed similar sentiments on behalf of himself and his wife: "Heidi and I are heartbroken by this heinous attack, and we are lifting up in prayer all the victims, their families, and the entire Midland-Odessa community."

Beto O'Rourke, a Democratic candidate for president and former congressman from El Paso, expressed his condolences on Twitter: "Our hearts are with Midland, Odessa and everyone in West Teas who has to endure this again. More information is forthcoming, but here's what we know: We need to end this epidemic."

Fellow presidential candidate Julián Castro, in Houston for a forum sponsored by the Islamic Society of North America, also said it was time to act against gun violence.

"My prayers are with our country and with West Texas tonight — not prayers that absolve us from inaction — but that we will each find the strength within us to act," he said. "To act boldly, swiftly, so that one day our grandchildren won't believe the stories of what these days were like."

Staff writer Dana Branham, The Associated Press, The Washington Post, Bloomberg News and the Lubbock Avalanche-Journal contributed to this report.