Updated at 10:01 p.m. ET
Twenty people are dead and 26 were wounded in a mass shooting at an El Paso, Texas, Walmart on Saturday morning, according to state and local authorities.
Speaking at a news conference, Gov. Greg Abbott said that what should have been a leisurely day of shopping "turned into one of the most deadly days in the history of Texas."
"We pray that God will be with those who've been harmed in any way," he added.
Unnamed officials identified the suspect as Patrick Crusius, according to The Associated Press. But neither Abbott nor other agency officials at a press conference on Saturday evening confirmed the suspect's identity.
They did say the suspect is a 21-year-old white male who traveled about 650 miles from Allen, Texas, to El Paso.
El Paso Police Department Chief Greg Allen said the suspect surrendered to authorities "upon being seen" outside of the Walmart where the shooting took place.
Allen said the department is working with state troopers and the FBI to determine whether the massacre in the diverse border community was a hate crime.
"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 without having seen all the evidence yet," Abbott said.
"We have to be very, very clear that conduct like this, thoughts like this, actions like this, crimes like this, are not who or what Texas is and will not be accepted here," the governor added.
Authorities in Texas offered no immediate details about the identities of the victims.
Mexican President Andrés Manuel López Obrador confirmed three Mexican nationals were among those killed in the attack.
El Paso borders Mexico's Ciudad Juarez, which has become a fulcrum of the migrant crisis, as asylum-seekers aiming to cross into the United States await processing.
"There is a fraternal coexistence between those who live in Ciudad Juarez and El Paso," López Obrador said in a videoposted to Twitter.
Mexican Foreign Minister Marcelo Ebrard tweetedthat six Mexicans were among the injured, including a 10-year-old girl.
The shooting marked the third major mass shooting in Texas in the past two years. In November 2017, 26 people were killed at a Baptist church in Sutherland Springs. The following May, 10 were killed at a high school in Santa Fe.
The motive of the shooter in Saturday's attack remains unknown.
Police are trying to learn whether a four-page manifesto that has surfaced online was written by the suspect.
FBI Special Agent in Charge Emmerson Buie said the agency is not ready to label the attack an act of terrorism or to declare a hate crime investigation.
Police say the shootings began at 10:39 a.m. local time, at the Walmart next to Cielo Vista Mall. Police were on scene six minutes later. Video from witnesses captured rapid and repeated firing inside the building.
Videos of what appears to be the apprehension are circulating online. They match surveillance images of a man walking into a building with a raised rifle.
Police Sgt. Robert Gomez said no law enforcement agents fired their weapons during the confrontation with the suspect.
Gomez added that most of the victims were wounded at Walmart, which was crowded with shoppers. He estimated that about 100 employees were in the store.