Two blasts were heard in the Thai seaside resort of Hua Hin on Friday, a Reuters witness said, just hours after two bombs killed one person and wounded 21 in the popular tourist destination south of Bangkok.
At least three people were wounded in one of the explosions on Friday, which occurred at around 9 a.m. (0200 GMT) near a clock tower in the popular, upscale resort, the Reuters witness said.
The latest blasts came after bombs that exploded late on Thursday killed one Thai woman and wounded 21 people, nine of them foreigners, Thai police said.
The twin sets of explosions happened as tourists flock to Hua Hin for a long weekend celebrated for the birthday of Thailand's Queen Sririkit, which is also Mother's Day in Thailand.
Small improvised bombs have been used frequently for attacks during periods of unrest over the past decade of political turmoil in Thailand.
However, such attacks have been rare since the military seized power in a May 2014 coup. Thais voted less than a week ago in a referendum to adopt a military-backed constitution, the first test of Prime Minister Prayuth Chan-ocha at the ballot box since he seized power in the 2014 coup.
One of the bombs exploded in a small lane near a bar at about 10.20 p.m. (1320 GMT) on Thursday, causing all the casualties, Hua Hin deputy police chief Samer Yousamran said.
A woman's shoe lay on the ground amid debris near a damaged street food stall at the scene on Friday, the Reuters witness said.
Samer said the first bomb on Thursday had exploded about 20 minutes earlier around 50 meters (55 yards) away.
Police were investigating and there was no immediate indication of a possible motive, he said. Police also believe both bombs were detonated using mobile phones
Check points have been established and security beefed up around Hua Hin and a royal palace in the resort. Police were due to hold a media conference on the attacks at 10.30 a.m. (0330 GMT) on Friday.
In a separate incident on Friday, Thai media reported two bombs had exploded in the southern province of Surat Thani, killing one person and wounding five.
Such blasts are common in the three Muslim-majority southernmost provinces of Thailand, where a bloody insurgency has killed more than 6,500 people since 2004. Hua Hin is far from the conflict zone, where attacks typically target security forces and not tourists.
The Muslim-majority region was part of a Malay sultanate until it was annexed by Buddhist-majority Thailand a century ago. Violence has occasionally spilled over to areas outside the three provinces.
The latest bombings came almost a year after an attack on a Hindu shrine thronged with tourists in central Bangkok killed 20 people and wounded more than 120. Thai police have accused two ethnic Uighur Muslims for the Aug. 17, 2015, attack.
Analysts, diplomats and even some officials suspected that attack was linked to sympathizers of the Uighur Muslim minority in western China, angered by the Thai junta's deportation of more than 100 Uighurs to China the month before that blast.
Thailand's 88-year-old King Bhumibol Adulayadej, the world's longest reigning monarch, and his wife Sirikit are in hospital in Bangkok but have resided in recent years in the Klai Kangwon Palace royal palace, which translates as "Far from Worries Palace", in Hua Hin.
King Bhumibol has received treatment for an infection over the past month in a Bangkok hospital, the Royal Household Bureau said on Aug. 1.
Concern about the health of the king and nervousness over the succession have played into the political tension.