On Monday, Thai police said they found bomb-making materials in a second apartment, after making an arrest Saturday in the Bangkok's deadly bombing, almost two weeks after the blast in killed 20 people.
Police found fertilizer, gun powder, digital clocks, and remote-controlled cars, which can all be used to make a bomb, during a raid over the weekend at an apartment in Bangkok's Min Buri district, national police chief Prawuth Thavornsiri said, according to the Associated Press.
"These are bomb-making materials," Prawuth said. "Nobody would keep urea fertilizer and gunpowder unless they wanted to make a bomb."
Thai police chief Somyot Poompanmuang said that the officer's would share an $83,000 cash reward for apprehending a suspect that has not yet been positively linked to the attack, Reuters reported.
"I insist that this is the work of the officers, the work they've accomplished, which led to the arrest, it's truly the work of the officers and their investigative abilities," Poompanmuang said. Two-thirds of the reward money was donated by an anonymous businessman and the remaining third came from the police chief himself.
Thai police on Saturday arrested a foreign man alleged to have explosives in his possession near the same neighborhood as the second apartment is located.
National police chief Somyot Poompunmuang told reporters the man's nationality has not yet been confirmed, but he was carrying a number of passports, including one from Turkey, according to the Bangkok Post.
"Authorities charged him with having explosives in his possession," the police chief told reporters, after allegedly discovering bomb-making materials in the man's apartment.
In a televised statement, police spokesman Prawuth Thavornsiri said the man was found to be in possession of detonators and metal pipes, the Associated Press reported.
More than 100 people were injured in the deadly Aug. 17 bombing at the Erawan shine, a popular tourist spot. An explosion in another part of Bangkok the following day did not result in any casualties.
"From our preliminary checks, [the man arrested] is related to both bombings," Thavornsiri said, according to the AP translation. "We believe he is a culprit in the same network."
Later on Monday, Prawuth said police had issued arrest warrants for two further suspects after bomb-making materials were found during the raid on the second apartment, AP reported.
The first new suspect is a 26-year-old Thai woman identified as Wanna Suansun, who is believed to have rented the second apartment in Min Buri. She also goes by the name Mai Saloh, and has a house registration in the southern province of Phang Nga, police said.
The second is a male who was also believed to be resident at the second apartment. He is of unknown nationality and was identified by Prawuth only as Jusuf, AP said.
After the shrine attack, authorities had released photos of a possible suspect, showing a man in a yellow shirt carrying a backpack.
Video footage appearing to show the man leaving a backpack at the shrine was also shared by Thai media.
Police later released a new detailed sketch of the suspect.
The blast took place near the five-star Grand Hyatt Erawan hotel and the popular Erawan Shrine near the busy Ratchaprasong intersection in the Thai capital at around 7 p.m. local time.
Thai Prime Minister Prayuth Chan-ocha called it the worst-ever attack on the country.
"This is the worst incident that has ever happened in Thailand," Prayuth said, according to AP.
"There have been minor bombs or just noise, but this time they aim for innocent lives. They want to destroy our economy, our tourism."
The shrine is to the Hindu deity Brahma, but it is also visited by thousands of Buddhists and tourists each day. It is located near three shopping malls in the city center's Chidlom district, the BBC reported.
One of the victims was identified as a British national.
CCTV footage of the blast was also shared thousands of times on Twitter.
Dashcam footage purporting to show the blast has also been widely shared on Facebook.
W. Patrick Murphy, the chargé d'affaires at the U.S. embassy in Bangkok, expressed his condolences to the victims.
Britain's ambassador called the attack "horrific."
In a statement, a spokesperson for U.N. Secretary-General Ban Ki-moon offered condolences to the Thai people:
The Secretary-General was shocked to learn of the explosion in Bangkok today close to the Erawan shrine and the loss of life of innocent civilians. He expresses his condolences to the bereaved families and to the people and Government of Thailand, and wishes those injured a quick recovery.
He hopes that those responsible will be brought to justice.
Attacks of this kind are extremely rare in the Thai capital. Two bombs were detonated outside a luxury shopping mall in February, but police said they were not intended to kill.
Thailand has been under military rule since a coup in May 2014.
The army chief turned prime minister, Gen. Prayuth Chan-ocha, has ruled without opposition since the takeover. An April report from the Washington Post said he had shown little commitment to a quick return to democracy in the country.
The Hindu deity Brahma is considered a god. An earlier version of this story incorrectly referred to Brahma as a goddess.