A shooting at a Walmart store in Texas left multiple people dead on Saturday with police warning that more than one gunman may have been involved in the attack.
At least one suspect was taken into custody after the shooting in the border city of El Paso, triggering fear and panic among weekend shoppers as well as widespread condemnation.
It was the second fatal shooting in less than a week at a Walmart store in the US and comes after a mass shooting in California last weekend.
Dan Patrick, the lieutenant governor of Texas, confirmed that there had been up to 20 casualties in the shooting at the Cielo Vista Mall after local television networks had reported similar numbers.
"We have between 15 and 20 casualties, we don't know the number of fatalities," Patrick told Fox News.
El Paso Mayor Dee Margo acknowledged that there had been a number of deaths after gunfire was first heard around 10 am.
"I can't confirm the number of fatalities. But there are fatalities," he told CNN.
"It is a tragedy and I don't want to comment until I have full information. It is a tragedy, I'm just so torn up about it."
Margo said three suspects were in custody, though police spokesman Sergeant Robert Gomez said he could confirm only one suspect in custody at the moment.
A witness who gave her name as Vanessa said she had just pulled into the parking lot at Walmart and "all of a sudden you heard what sounded like fireworks, really loud fireworks."
"You could hear the pops, one right after another and at that point as I was turning, I saw a lady, seemed she was coming out of Walmart, headed to her car. She had her groceries in her cart and I saw her just fall," she told Fox News.
The witness told Fox that she had seen one man open fire wearing what appeared to be combat fatigues.
"He was wearing a black t-shirt, camo colored pants. He was wearing something to cover his ears, like headphones, really thick ones.
"He was carrying a dark rifle and he was just pointing at people and just shooting and, yeah, the last thing I saw, he shot somebody that was in a corner."
After seeing the woman fall in the parking lot, "that's when I thought, okay, this is not -- these aren't fireworks ... He was just shooting randomly. It wasn't to any particular person. It was any that would cross paths."
The White House said President Donald Trump, who is spending the weekend at his golf club in New Jersey, had been told about the shooting.
"The President has been briefed on the shooting in El Paso, and we continue to monitor the situation," White House Deputy Press Secretary Steven Groves said in a statement.
Trump had spoken to Attorney General Bill Barr and Texas Governor Greg Abbott about the shooting.
Abbott called the shooting "a heinous and senseless act of violence," adding that "our hearts go out to the victims."
It has been a particularly bad week for gun violence in the United States.
Two people died and a police officer was wounded Tuesday at a Walmart in Mississippi.
Last Sunday a 19-year-old gunman opened fire at a food festival in northern California, killing three, including two children.