Thai police said on Tuesday investigators believe a man seen in security video wearing a yellow T-shirt and carrying a backpack set off the explosion at a central Bangkok shrine that killed 21 people and injured more than 100. “The yellow shirt guy is not just the suspect. He is the bomber,” Police Lieutenant General Prawut Thavornsiri, told reporters on Tuesday. Prawut earlier released several photos of the man, with and without the backpack, on a social media platform. The images were apparently taken from closed-circuit video at Erawan Shrine on Monday before the central Bangkok bombing. He confirmed that the man is suspected in the bombing. Video footage posted separately on Thai media appeared to show the same man sitting on a bench at the crowded shrine, then taking off the backpack and leaving it behind as he walked away. Watch: Thai Police release video of Erawan Shrine bombing suspect National police chief Somyot Pumpanmuang said the suspect, seen in a first CCTV image with a backpack and then in a later one without the bag, could be Thai or a foreigner. “That man was carrying a backpack and walked past the scene at the time of the incident. But we need to look at the before and after CCTV footage to see if there is a link,” Somyot told a news conference. The government said the attack during the Monday evening rush hour, which killed 21 people including nine foreigners from several Asian countries, was aimed at destroying the economy. No one has claimed responsibility. Raising tensions in the city on Tuesday, a small explosive was thrown from a bridge over a river but no one was injured, a police officer at the scene said. Police earlier said they had not ruled out any group, including elements opposed to the military government, for the bombing at the Erawan Shrine on Monday evening, although officials said the attack did not match the tactics of Muslim insurgents in the south. Prime Minister Prayuth Chan-ocha also referred to the man as a suspect without giving details. He said there were “still anti-government groups out there”, although he did not elaborate. Police were deployed to the blood-splattered site on Tuesday, some wearing white gloves and carrying plastic bags, searching for clues to an attack that could dent tourism and investor confidence. The Thai baht fell 0.57 per cent to 35.57 baht, its weakest in more than six years, on concern the bombing may scare off visitors. Thai stocks fell as much as 3 per cent. Police said the death toll was 22, with 123 people wounded. They said the blast was caused by a pipe bomb. “Police are not ruling out anything including [Thai] politics and the conflict of ethnic Uygurs who, before this, Thailand sent back to China,” Somyot said. Thailand forcibly returned 109 Uygurs to China last month. Hundreds, possibly thousands, of the Turkic-speaking and largely Muslim minority have fled unrest in China’s western Xinjiang region, where hundreds of people have been killed, prompting a crackdown by Chinese authorities. Many Uygurs have travelled through Southeast Asia to Turkey. The blast comes at a sensitive time for Thailand, which has been riven for a decade by a sometimes violent struggle for power between political factions in Bangkok. READ NOW: Thailand's PM says police hunting male Bangkok bomb suspect in 'country's worst attack' that left 21 dead An interim parliament hand-picked by a junta that seized power in a last year coup is due to vote on a draft constitution next month. Critics have criticised the draft as undemocratic and say it is intended to help secure the military’s grip on power and limit the influence of elected politicians. The attack also comes as Prayuth, under pressure to get the economy in shape, prepares to reshuffle his cabinet. Senior ministers have dismissed the possibility of the bomb attack being related to the cabinet reshuffle. The Erawan Shrine, on a busy corner near top hotels, shopping centres, offices and a hospital, is a major attraction, especially for visitors from East Asia, including China. Many Thais also worship there. Four Chinese, including two people from Hong Kong, were among the dead, China’s official Xinhua news agency said. Two Malaysians, a Singaporean, an Indonesian and a Filipino were also killed, officials said. Scores of people were wounded, including many from China and Taiwan. Occasional small blasts over recent years have been blamed on one side of the domestic political divide or the other. In February, two pipe bombs exploded outside a shopping mall in the same area as the Monday blast but caused little damage. Thai forces are also fighting a low-level Muslim insurgency in the predominantly Buddhist country’s south, but those rebels have rarely launched attacks outside their heartland. “This does not match with incidents in southern Thailand. The type of bomb used is also not in keeping with the south,” army chief and deputy defence minister General Udomdej Sitabutr said in a televised interview. Tourism is one of the few bright spots in an economy that is still struggling, more than a year after the military seized power in May last year. It accounts for about 10 per cent of the economy and the government had been banking on a record number of visitors this year following a sharp fall last year because of protests and the coup. In Washington, the US State Department said it was too soon to tell if the blast was a terrorist attack. Spokesman John Kirby said authorities in Thailand had not requested US help.