A gunman entered a shopping mall in El Paso, on the Mexican border in the state of Texas, opened fire randomly around.

Authorities said on Saturday the suspect was arrested outside a Walmart store near the Cielo Vista Mall, eight kilometers from a border checkpoint with Mexico. 

Police confirmed that a 21-year-old from Allen, Texas, was the only person in custody. US media identified the suspect as Patrick Crusius, a white male. Police said he is believed to be the only shooter. 

Mexico President Andres Manuel Lopez Obrador said three Mexicans had been killed in the shooting and Foreign Minister Marcelo Ebrard said on Twitter six others were wounded.

El Paso in West Texas, which has about 680,000 residents, sits across the border from Juarez, Mexico. The county is more than 80 percent Latino and Mexican citizens legally pass the border every day to work and shop in the US. 

Speaking to reporters, Texas Governor Greg Abbott said: "We are going to aggressively prosecute it both as capital murder but also as a hate crime, which is exactly what it appears to be."

ILKHA