Texas Gov. Greg Abbott confirmed that 20 people were killed and more than 24 injured in a shooting at a commercial complex in El Paso.
A gunman killed several people at a Wal-Mart store in El Paso, Texas on Saturday, and police detained a suspect after the latest random shooting in the United States that prompted shoppers to flee.
Many of those who witnessed the incident were buying back supplies for schools.
Sergeant Robert Gomes of El Paso police told reporters that the authorities had ruled out the idea of more than one absolute fire, adding preliminary reports indicated the gunman had used a gun.
He said the suspect was a young man in his 20s and was arrested by the police without resistance.
The KTSM television station in El Paso posted on its Web site what it described as two photographs taken by security cameras when Wal-Mart entered.
A young man with glasses on his eyes, wearing trousers, a dark shirt and a gun appeared in the pictures. He was putting his ears on his ears.
For his part, US President Donald Trump on his Twitter account, reports from El Paso "very bad because many have died."
Parliament member Veronica Escobar, a Democrat from El Paso, told CNN that the number of victims was "shocking".
The El Paso police department said the situation was still evolving around the Selo Vista Mall, close to Wal-Mart, but that it was not a direct threat to people's lives.
People who can not contact their families were asked to go to a family reunion center at a junior high school instead of going to the mall.
Texas Attorney General Kean Paxton said the death toll from the shooting was between 15 and 20.