Thailand's prime minister on Wednesday vowed "preventive measures" after a shooting at a Bangkok shopping mall left two people dead and raised fresh questions about the kingdom's gun control.

Shoppers returned in dribs and drabs as the Siam Paragon mall reopened less than 24 hours after the shooting -- Thailand's third high-profile deadly gun attack in four years.

The shooting at one of Bangkok's biggest, most upmarket malls will come as a fresh blow to the kingdom's efforts to rebuild its vital tourism industry after the pandemic.

Prime Minister Srettha Thavisin joined a minute's silence at the mall before offering the government's condolences to the families of the two female victims -- one Chinese and one from Myanmar.

"I am confident Siam Paragon and government officials did their best to minimise the casualties and damage," he said.

"Let this be the only time this happens. My government insists we will give priority to preventive measures," he added, without giving details.

Police arrested a 14-year-old suspect, a student at a $4,000-a-term private school just metres from Siam Paragon.

Investigators say the boy was being treated for mental illness, has not been taking his medication and reported hearing voices telling him to shoot people.

- Past promises -

Samran Nuanma, Assistant National Police Chief, told a news conference on Wednesday that the weapon used in the attack was a blank-firing pistol.

"But the barrel was modified for live shooting," Samran said.

"We will increase regulations and laws to control the use of firearms."

But repeated promises of tightening gun laws in the past have not prevented tragedies. 

The Siam Paragon shooting came just days before the anniversary of a massacre at a nursery in northern Thailand that left 36 people dead.

And in 2020, a former army officer gunned down 29 people in a rampage at a mall in the northeastern city of Nakhon Ratchasima.

By one estimate, Thailand has 10 million guns in circulation -- one for every seven citizens, and one of the highest rates of ownership in the region.

Many firearms are smuggled into the country, but Kritsanapong Phutrakul, a former police officer and now academic, said internet sales were becoming a problem.

"Only a small number of police officers have the knowledge, capabilities and experience to track the gun market online," he told AFP.

- Tourism impact -

Thailand is desperate to rebuild its tourism sector after travel restrictions during the Covid-19 pandemic saw visitor numbers dwindle.

China -- which sent around 10 million visitors a year before the pandemic -- is a crucial market, but numbers are not returning as fast as Thai officials would wish.

This is partly because of fears in China about whether Thailand is a safe holiday destination, and the fact one of the mall shooting victims was Chinese is unlikely to improve this situation.

Srettha spoke to the Chinese ambassador late Tuesday and issued a statement saying the government would implement "the highest safety measures" for tourists.

At Siam Paragon on Wednesday, AFP reporters saw that security was stepped up in some places, with bags being searched -- but not on all entrances to the sprawling mall.

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