A reported 20 people were shot dead and 26 injured in a gun shooting massacre inside a Walmart in the Cielo Vista Mall in El Paso, Texas, on Saturday. One suspect has been detained after surrendering to police.

Earlier on Saturday, witnesses said, cited by local media, that they heard multiple gunshots, and claimed that there were several people with guns at the Walmart. Social media users posted footage said to be at the scene of the massacre.

At 11:03 am local time (15:03 GMT) El Paso police reported that they had responded to an active shooting near the Cielo Vista Mall and urged people to stay away from the area. Over an hour later, police said the scene was still active and confirmed that they had received reports of multiple shooters.

Later on Saturday, Police Sgt. Enrique Carrillo told reporters that the attack had ended.

The Federal Bureau of Investigation in El Paso also confirmed that they had responded to the Walmart gun massacre and were "assisting and coordinating with El Paso police".

According to the governor of Texas, 20 people have been killed and another 26 injured in the shooting. The incident may be classified as capital murder and a hate crime, El Paso Police Chief Greg Allen said during a news conference.

Eleven people injured in the shooting were taken to Del Sol Medical Center, where nine remain in critical condition, hospital spokesman Victor Guerrero said.

Two of them are stable condition, nine of them are critical, but stable condition. Age ranges from 35 to 83 years old", Guerrero said.

US President Donald Trump on Saturday described the El Paso Walmart gun massacre a "cowardly" and "hateful" act.

El Paso, which has about 680,000 residents, is in southwest Texas and sits directly across the border from Juarez, Mexico.