BANGKOK — Thai police issued arrest warrants Monday for two more suspects, a Thai woman and a foreign man of unknown nationality, and released their images in the widening investigation into Bangkok’s deadly bombing two weeks ago that yielded its first arrest over the weekend.

National police spokesman Prawuth Thavornsiri said he was certain the two were part of a group police say was responsible for the Aug. 17 blast at the Erawan Shrine in central Bangkok that killed 20 people, more than half of them foreigners .

During a televised statement on Monday, Prawuth displayed a photograph of the woman’s Thai identification card showing a young woman in a black headscarf and a sketch of the man. He later said police were asking for additional arrest warrants.

The development came after police arrested a man from an apartment in Bangkok’s outskirts on Saturday and seized bombmaking equipment that included detonators, ball bearings and a metal pipe believed to be a bomb casing .

Thai police, meanwhile, awarded themselves an $84,000, reward Monday for tips leading to the arrest of bombing suspects.

National police chief Somyot Poompanmoung said he was taking the unusual step of giving the reward to the police force both to motivate his officers and to show that Thailand’s police are good at their job.

“This money should be given to officials who did their job,” he said at a news conference as aides brought out stacks of 1,000 baht notes. It wasn’t immediately clear how the money would be distributed to police officers.

More bomb-making materials were discovered in a second apartment during a raid Sunday in a nearby neighborhood, said Prawuth. He said the second apartment, in a neighborhood known as Min Buri, was rented by the Thai woman identified as 26-year-old Wanna Suansun. He said the woman has a house registration in the southern Thai province of Phang Nga, and is also known by the name Mai Saloh.

Prawuth described what police found in the second apartment as “important bomb-making materials such as gunpowder, ureabased fertilizer which can be used as explosive powder when mixed with other substances, a remote-controlled car with its controller which can be used as a detonator, nuts and bolts, small light bulbs and digital watches,” among other things.

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