Washington: A man went on a rampage at a Texas outlet mall on Saturday, shooting dead eight people and wounding several others before he was killed by a police officer at the busy shopping complex.

Video footage circulating online showed the shooter getting out of a sedan in the mall's parking lot before opening fire on people walking nearby.

An officer inside on an unrelated call quickly responded to the gunfire and "neutralized" the shooter as scenes of panic broke out at the sprawling facility in Allen, police said.

The identity of the shooter was not released. His body, sprawled on a sidewalk, was one of seven deaths at the mall when more police arrived.

Two others died in the hospital while "three are in critical surgery, and four are stable," said Allen fire chief Jonathan Boyd.

The shooting at Allen Premium Outlets, 35 miles (55 kilometers) north of Dallas, began around 3:30 pm (2030 GMT), when it was busy with weekend shoppers, police said.

The officer in the mall "heard gunshots, went to the gunshots, engaged the suspect and neutralized the suspect," said chief Brian Harvey of the Allen police department.

Some of the victims were as young as five years old, a hospital official told NBC News.

Texas Governor Greg Abbott called the mass shooting an "unspeakable tragedy."

President Joe Biden "has been briefed on the shooting," a White House official told reporters.

Local officials hailed the actions of the police officer who charged and killed the shooter.

"We owe a debt of gratitude to first responders that ran toward the gunfire and acted swiftly to neutralize the threat," said Keith Self, a Republican congressman whose district includes the city of Allen.

Authorities believed initially that a second shooter might be on the loose. As police combed through stores in the mall, frantic shoppers and store employees rushed into parking lots.

Harvey later said police believe the unidentified shooter, who CNN said was wearing tactical gear, "acted alone."

Janet St. James, a spokesperson for Medical City Healthcare, which operates multiple trauma facilities in North Texas, said it received eight patients from the shooting, ranging in age from five to 61, NBC News reported.

"Allen is a proud and safe city which makes today's senseless act of violence even more shocking," mayor Ken Fulk said in a statement.

"I want to commend our police and fire departments for their quick response. Their thorough training not to hesitate to move toward the threat likely saved more lives today."

-'No more safe places' -

Jaynal Pervez, who arrived at the mall while his daughter was inside, told CNN: "There's no more safe places. I don't know what to do."

Pervez later told broadcaster CBS that the scenes in the mall parking lot had been chaotic.

"I saw the shoes around there, people's cell phones on the street," he said.

With more firearms than inhabitants, the United States has the highest rate of gun deaths of any developed country -- 49,000 in 2021, up from 45,000 the year before.

There have been more than 195 mass shootings -- defined as four or more people wounded or killed -- so far this year in the United States, according to the Gun Violence Archive.