Thai Prime Minister Prayut Chan-o-cha (center) talks to an individual injured in the shooting incident at the Terminal 21 shopping mall in Nakhon Ratchasima on Sunday. Photo: AFP

A Thai soldier angry over a land deal went on a shooting spree that killed at least 26 people, most of them in a shopping mall in the northeast that he fled to in a stolen Humvee after shooting his commanding officer, officials said.

Thai security forces shot and killed the rogue soldier on Sunday morning after an overnight standoff at the Terminal 21 shopping center in the northeastern Thai city of Nakhon Ratchasima

The soldier was armed with an assault weapon and ammunition stolen from the army base's arsenal, an official said.

He initially posted written messages on Facebook during the attack before his account was shut down by the company.

Hundreds of shoppers fled the mall in groups crouching low, and the police and army launched several rescues during the more than 12-hour standoff, with armed forces at one point emerging at a run carrying small children.

"It was frightening because I could hear the occasional gunshot... we waited a long time for the police to come and help us, many hours," said Suvanarat ­Jirattanasakul, 27, her voice trembling after she emerged.

Another shopper who escaped told local Amarin TV that the shooter was "aiming for the heads" and said his colleague died on the scene. "I heard so many gunshots. He was shooting everywhere and his shots were very precise," said the man, identified as "Diaw."

Police named the shooter as 32-year-old soldier Jakrapanth Thomma. He reportedly worked at an army base close to Nakhon Ratchasima, which is about 250 kilometers from the capital Bangkok.

Thai media said the suspect was a sharp shooter and gun enthusiast who often posed with weapons on social media.

The killings began at around 3 pm on Saturday when the soldier opened fire in a house before moving to an army camp and then to the mall.

"It was a personal conflict... over a house deal," Prime Minister Prayut Chan-o-cha told reporters on Sunday from ­Nakhon Ratchasima after traveling there to meet with wounded survivors.

Prayut added that the conflict was with a relative of the soldier's commanding officer.

The commanding officer was one of the people reported killed before the soldier moved on to the shopping mall and began shooting.

Hours before he began shooting on Saturday, Jakrapanth had posted on his Facebook account denouncing greedy people.

"Rich from cheating. Taking advantage of other people. Do they think they can spend the money in hell?" read one post in Thai.

He later posted written updates during the attack.

"Death is inevitable for everyone," he wrote. Later, he complained about his fingers cramping and asked "Should I give up?" before the account was no longer available.

Hours after the mall siege began, Facebook said it had removed the suspect's account.

According to the the Chinese Consulate General in Khon Kaen, Thailand, two Chinese citizens were in the mall at the time of the shooting. They were unhurt and were safely evacuated early Sunday morning.