Police check the scene after two bomb blasts in the southern province of Surat Thani, Thailand in this still image from video August 12, 2016. [Photo/Agencies]

BANGKOK - Four people were killed and 31 others injured in separate blasts at tourist spots and other places in southern Thailand on Friday, police said.

Explosions took place in Phuket and Hua Hin, viewed as Thailand's favorite tourist destinations, and elsewhere in the southern region of the country. The police were investigating the blasts at the usually peaceful spots while unknown bombing suspects are still at large.

The four deceased victims were identified as Thai nationals while the 31 injured, many of whom foreign travelers, were rushed to hospital, the police said.

Security has been tightened in and around the blast scenes for fear of repeated violence while local villagers and tourists were strongly advised to stay in their homes and lodging units.

The remotely detonated explosions were apparently planted in the Friday rush hours during which there were not so many people at the world-famous tourist resorts such as Phuket and Hua Hin, otherwise the casualties could have been far more grave, the police said.

In an earlier incident, one person was reportedly killed and several others injured on Thursday when a possibly drive-by bomb was hurled at a marketplace in Trang province.

Besides, blazes broke out in the southern provinces of Krabi, Trang, Pang-nga and Nakorn Sri Thammarat but no deaths or serious injuries were reported.

The fires took place on the premises of department stores in Nakorn Sri Thammarat and Trang and at marketplaces and shopping areas in Pang-nga and Krabi.

The police said the blasts and blazes were acts of arson and sabotage but did not either confirm or deny they might possibly have been connected with Thailand's political situation, in which a new constitution was adopted at a nationwide referendum on Sunday.

Deputy Premier and Defense Minister Prawit Wongsuwan summoned high-ranking security officials and other government personnel for an emergency meeting in bid to cope with the blasts and blazes in southern Thailand.

The south of Thailand is widely known as the biggest stronghold of the Democrat Party, whose members and supporters were believed to have voted for the new charter in the referendum and hometowns of former premier Chuan Leekpai and former deputy premier Suthep Thuaksuban, who had led a massive movement in Bangkok streets which eventually prompted Premier Prayut Chan-o-cha to orchestrate a 2014 military coup to depose the besieged government led by then-premier Yingluck Shinawatra.