A Thai soldier has killed at least 20 people and wounded 31 in a shooting rampage in the northeastern city of Nakhon Ratchasima, according to the health ministry.
The suspect of Saturday’s attack, identified by police as Sergeant Major Jakrapanth Thomma, remains at large, and Thai police entered a shopping centre he was hiding in.
Dozens of terrified shoppers were evacuated from the centre as armed police said they had “taken control” of the ground floor of the complex.
But authorities did not give any firm details on the whereabouts of the attacker.
“There are about 20 dead,” Kongcheep Tantravanich, defence ministry spokesman said.
The suspect reportedly stole an army vehicle and posted photos and video of himself in full tactical gear as the attack was carried out.
He wrote on his Facebook page earlier in the day that “Death is inevitable for everyone”. The suspect also posted a picture of what appeared to be his hand holding a gun.
At one point after the shooting had begun, he wrote online, “Should I give up?” before his account became inaccessible.
The soldier opened fire at different locations in the city, which is more than 250km (155 miles) from capital, Bangkok, police spokesman Kissana Phathanacharoen said in a message sent to reporters.
The shooter remained in a shopping centre and had not yet been apprehended, the police said.
“We don’t know why he did this. It appears he went mad,” said defence ministry spokesman Kongcheep Tantrawanit.
Al Jazeera’s Wayne Hay, reporting from Bangkok, said that the situation around the shopping centre was still evolving.
“Police say that the suspect has hostages inside the shopping centre with him, but it is not clear how many,” he said.
Hay added that some people left the centre, escorted by the police, and gun shots were heard from the building in the evening hours.
Local media showed footage of the soldier getting out of a car in front of the shopping centre and firing a series of shots.
Footage circulating online showed panicked scenes, with people fleeing and what appeared to be the sound of automatic gunfire filling the air.
One video from a bystander showed a man slumped at the wheel of a car in a pool of blood. It was unclear if he was among the dead.
A woman interviewed by Thailand‘s Channel One television said she had heard gunshots when she was at the shopping centre and hid in a clothing store with other people before escaping.
The shooter had initially gone to a house in the city and shot two people dead, before going to the weapons store on an army base and taking a new gun, police said.
They added that he also shot at people on the army base.
Thai army chief Apirat Kongsompong issued an order for local army commanders to rush to the scene and investigate.
Prime Minister Prayuth Chan-ocha expressed condolences to the families of those killed, a government spokeswoman said.
Thailand has one of the highest rates of gun ownership in the world but mass shootings by soldiers targeting civilians are rare.
Several shootings at courthouses late last year also renewed concern about gun violence in the country.
In one high-profile case, two lawyers were shot dead by a clerk at a court in eastern Thailand during a hearing over a land dispute.