Hundreds of people were taken out of the "Headquarters of the Massacre of Thailand." The attacker is still at large.

A spokesman for the Ministry of Defense of Thailand told "Reuters" that members of the police and army stormed a shopping center sheltered by an armed attacker, and helped hundreds of people escape after the attacker fired indiscriminately.

"The police and soldiers are carrying out a joint operation, and they have helped hundreds of people leave the mall. The number of people remaining inside the center is unknown," the spokesman added.

He said the suspected gunman was still inside the Terminal 21 commercial center in Nakhon Ratchasima Province, northeastern Thailand.

The newspaper "Bangkok Post" reported that an army soldier shot, on Saturday evening, soldiers and civilians, killing at least 20 people, wounding others, and being held hostage in a local mall.

There are "20 deaths and 14 wounded," said an official, who was not named, from the Erawan Center in the capital, Bangkok, which is a nationwide emergency services center.

"The massacre started when the bomber stole weapons and ammunition, and his commander and two others were shot dead at the Surathmac army camp, before he escaped in a military Humvee," the Bangkok Post says.

Along the road to the "Terminal 21" shopping center in Muang District, the soldier shot civilians.

"The gunman used a machine gun, and he shot innocent victims, resulting in many deaths and injuries," said police spokesman Chrisana Pattanacron.

The sheltered armed attacker posted his picture on Facebook during the attack

Local media showed a video of the soldier exiting the car in front of the mall at around 6 pm local time, firing a number of shots, and people rushed to try to take shelter from the bullets that could be heard in the video.

The attacker then fired at the cooking gas cylinder, which resulted in an explosion and fire. The video clips showed people running and rushing behind the cars.

Unconfirmed reports said the soldier was in possession of grenades.

Inside the mall, the soldier used the live Facebook feature, and posted a selfie with a gun. "I am exhausted, I cannot move my fingers," he said in a video released at 7:20 pm local time.

The authorities sent special forces to the mall, where the attacker was said to be holding 16 hostages on the fourth floor.

A crime-fighting police commando was also seen at the site, and the police were trying to move the soldier's mother to the scene, in the hope that she could persuade him to surrender.

At approximately 8:30 pm local time, the Special Forces were reportedly preparing to "engage" with the shooter inside the shopping center. The army has asked the media to stop live coverage to avoid giving suspects information about what is happening.