A man was arrested following a shooting incident that killed one and injured another in a government office outside Bangkok, days after a student opened fire at his school and family home in the same province, killing at least eight people.

The shooting occurred at around 11am at the offices of the Nonthaburi Provincial Administrative Organisation on Monday, according to the provincial public relations department.

It said the suspect, identified as Chalong Riewraeng, a former legislator, was arrested.

Thongchai Yenprasert, chief executive of the organisation who police believe was the target, died from critical wounds at a hospital after being shot in the face and neck, while his driver was shot in the arm and is in a stable condition, officials said.

Regional police commander Wattana Yeejeen said the suspect had admitted to the shooting and that the motive is believed to be personal.

Chalong told reporters at a local police station that he was arguing with Mr Thongchai over money he had lent him.

He said he followed Mr Thongchai to his car before drawing his weapon.

He said he did not intend to shoot Mr Thongchai, but the driver also drew a gun and pointed at him, prompting him to open fire.

“I wanted to apologise to the people of Nonthaburi,” he said. “I had no intention. We were friends and I thought we could talk it out, but he wouldn’t talk to me.”

The incident drew particular attention as it happened just days after a 14-year-old student allegedly killed at least eight people in a shooting at Debsirin Nonthaburi School and his home on Friday, before apparently taking his own life.

A 12-year-old schoolgirl and five school staff were killed by the attack at the school, while the boy also appeared to have killed his two grandparents at his family home earlier in the morning, officials said.

Atthapol Anusit, deputy regional police commander, said on Sunday that police had interviewed several witnesses but had not yet determined the motive for the attack.

He said the boy appeared to have faced several problems involving his family and school.

Police investigation of the boy’s electronic devices also found that he had consumed violent content on social media and had a search history indicating an interest in firearms dating back about one to two years, Commander Atthapol said.

Witnesses told police that the boy last year had brought a BB gun to the school, which was later confiscated by a teacher, he said.

Thailand has one of the highest rates of gun ownership in Asia, second only to Pakistan and far surpassing its south-east Asian neighbours.

Data collected in 2017 by the groups Small Arms Survey and GunPolicy.org in their last extensive international study found civilian gun ownership in Thailand was about 15.1 guns per 100 people, compared with less than one per 100 in neighbouring Malaysia.

Thailand had 3.49 deaths by firearms per 100,000 people, according to 2023 statistics published by World Population Review.

That puts it well behind parts of Latin America and the Caribbean, but relatively high in Asia.

Only the Philippines is higher in south-east Asia.

While shootings involving indiscriminate killings are not common, the country has seen an uptick in high-profile shooting deaths in recent years.

In February, a 17-year-old stole a gun from police and opened fire at a public high school in southern Thailand, briefly taking people hostage in a two-hour attack that killed one person and wounded two others.

A 14-year-old boy was accused of a 2023 shooting at a major Bangkok shopping mall.