A Thai soldier who rampaged through a bustling shopping mall and a nearby army camp, killing at least 21 people, has been fatally shot by security forces, an official said.

"The police have killed the perpetrator and rescued eight hostages. Some were wounded," said one of the security sources.

Both declined to be named because they were not authorised to speak to the media.

The sergeant engaged police in an hours-long standoff in Thailand after he reportedly shot his commanding officer, took several military firearms and drove a stolen Humvee to a mall.

The chaotic violence triggered a tense standoff with the gunman, who was holed up in the mall into the early morning. The alleged shooter, toting an assault rifle and clad in camouflage and a helmet, was identified by authorities as 32-year-old Jakrapanth Thomma, a sergeant in the Thai military.

The attack is at least the second mall shooting in Thailand this year. On January 9, a masked gunman fatally shot three people, including a 2-year-old boy, while he robbed a jewelry store in the city of Lopburi, the Associated Press reported. A suspect was arrested, reportedly confessed and said that he had not meant to shoot anyone, according to the AP.

Saturday's violence began around 3:30 pm local time, when police say Thomma fatally shot his commanding officer, took several military firearms and drove about 14km in a stolen Humvee to the Terminal 21 mall in Nakhon Ratchasima, where he fired at shoppers and drivers on the packed roadways. The city, also known as Korat, is about three and a half hours by car from Bangkok.

The precise movements of the gunman throughout the city remain unclear. Authorities have not said how many people died at the army camp and how many were killed at the shopping mall. At least 31 people were reported injured.

A police officer in Nakhon Ratchasima told the AP by phone that the killing began when the alleged gunman fatally shot another soldier and a woman and wounded a third person before he escaped with guns and ammunition.

Police said they retrieved the shooter's mother from neighboring Chaiyaphum province, about 60 miles away, and planned to use her to negotiate with the suspect.

"We don't know why he did this," Thai Defense Ministry spokesman Kongcheep Tantrawanit told Al Jazeera. "It appears he went mad."

It is relatively easy to legally obtain a gun in Thailand. Beyond military use, a prospective gun owner needs to show a valid reason for owning a gun, such as hunting or self-defense. The minimum age to own a gun in Thailand is 20, and the owner must pass a criminal-background check.

The annual rate of gun deaths in 2016 in Thailand was 2.54 per 100,000 people, according to the University of Sydney's School of Public Health. The rate in the United States was 11.96 deaths per 100,000 people in the same year. Over the past several years, the total number of gun deaths in Thailand has decreased from 3,420 in 2007 to 1,729 in 2016.