NASHVILLE, Tennessee (REUTERS/AFP) - A gunman also wielding an axe opened fire at a Nashville-area theatre showing of the movie Mad Max: Fury Road and was shot dead by police after slightly injuring at least one person on Wednesday, police and fire officials said.

More than a dozen emergency vehicles were on the scene at the Carmike Hickory 8 movie complex in Antioch, where one man suffered minor injuries from the axe and that man and two women were treated for exposure to pepper spray, possibly from the gunman, officials said.

"We believe the imminent threat has been ended," police spokesman Don Aaron told reporters.

The gunman, a 29-year-old unnamed local white man, also wore a backpack that was strapped to the front of his body, and the authorities were going through it to make sure that it did not pose a danger. He was armed with a pellet gun, the Nashville Police Department said on Twitter.

Mr Brian Haas of the Nashville Fire Department said none of the injuries, including the axe wound, appeared to be serious and none of the victims were transported to area hospitals. "It appeared to be nothing but a bad bruise," he told reporters referring to the person struck by the axe.

Two employees of a nearby Starbucks restaurant said they heard three or four gunshots and saw several police, fire trucks and ambulance vehicles responding.

With only the attacker killed and three others slightly hurt, the authorities said the outcome could have been much worse, hailing the rapid response of police who were at the theater in mere minutes, potentially saving dozens of lives.

"He had two backpacks. The one that remained on his person had what you might term as hoax device. It was a device configured to look like an explosive. It was not," Nashville police chief Steve Anderson told reporters.

A second backpack left at the scene was also deemed not threatening, Mr Anderson said.

The shooter - who police originally said was 51 - entered the theater, where "Mad Max: Fury Road" was playing, and fired pepper spray at viewers before an officer burst in through the projection room, followed by a SWAT team.

The police officer shot at the man, who took aim back before fleeing through a back door of the cinema, where he ran into several more officers.

"He was shot, fatally wounded, and has been pronounced deceased at the scene," said Nashville police spokesman Don Aaron.

The mask worn by the shooter may have been used to protect him from the chemical spray, according to Aaron.

A shaken witness who was reportedly struck with pepper spray along with his daughter thanked police for saving their lives.

"I'm very, very grateful that no one else got injured here today, other than the person who perpetrated this," he said, without providing his name.

"I would ask anyone to pray for his family because he obviously has some mental problems or something else."

A 58-year-old man sustained "superficial" injuries to his shoulder and arm from the hatchet and was also hit with the pepper spray, said Nashville Fire Department spokesman Brian Haas.

Two women, aged 17 and 53, were hit in the face with the spray, but no one else was being transferred to area hospitals and the area was later deemed safe.

The shooting comes less than two weeks after three people were killed and nine were wounded when a gunman opened fire in a movie theatre in Lafayette, Louisiana.

The gunman was among the dead.

In the Lafayette incident, the 59-year-old gunman opened fire on July 23 in a movie house during a showing of the comedy Trainwreck.

Two cinemagoers were killed before he took his own life as police closed in.

That shooting came almost three years to the day after 12 people were slain and dozens wounded by a gunman at a cinema in Aurora, Colorado, during a midnight screening of the Batman film The Dark Knight Rises.

The Nashville shooting follows the fatal shooting of five US servicemen in Chattanooga, Tennessee, and the massacre of nine African Americans at a South Carolina church.