A powerful explosion sent a fireball and hail of debris through a busy Bangkok district filled with shoppers and tourists Monday, killing at least 19 people near a site that also has been a hub for political rallies and clashes, police said.

More than 120 people were reported injured in what authorities described as a bomb blast, and one police official said many foreigners were among the casualties.

There was no assertion of responsibility for an attack whose location — near one of the city’s tourist and commercial crossroads — and timing — shortly before 7 p.m. — may have been chosen to maximize damage and bloodshed.

Such attacks in Bangkok are rare, but tensions have risen as Thailand’s military-backed leaders tighten their grip on power. Muslim separatists have carried out attacks in the past, but far from the capital of this Buddhist-majority nation.

There were conflicting accounts on the nature of the bomb. Police officials said it was formed from a pipe wrapped in cloth, the Associated Press reported. They later said the device was fastened to a utility pole near the Erawan Shrine and detonated at 6:55 p.m., causing two nearby taxis to explode.

Earlier, Aek Angsananond, the deputy national police chief, was quoted as attributing the blast to a “motorcycle bomb.” The comment suggested that the device could have been stashed on a motorcycle near the Hindu shrine, which is close to a popular shopping and tourist area in central Bangkok and draws a steady stream of worshipers and other visitors, including foreign tourists.

The nearby Ratchaprasong intersection has been a staging area for political demonstrations between powerful rival factions in recent years. In 2010, security forces stormed the streets in a bloody crackdown against supporters of ousted prime minister Thaksin Shinawatra.

Also nearby are several installations of the Royal Thai Police, as well as the state-run Police General Hospital.

At least two other explosive devices were found in the area and defused by bomb-disposal experts, authorities said.

“We believe it may be a timer bomb,” said Pusit Chanacompoo, a member of a volunteer ambulance organization who was across the street when the explosion occurred.

“It was horrible,” Pusit said. “I see so much blood doing my job, but I had a very hard time looking at all the bodies.”

Immediately north of the shrine, body parts and wreckage from motorbikes and cars were strewn across Ploenchit Road. Authorities covered the body parts with white cloth and blocked off streets about 200 yards in each direction. Two hours after the blast, police and military personnel were still collecting remains from sidewalks and streets.

One emergency worker said a hand was found on the fifth floor of a nearby building.

“There were bodies everywhere. Some were shredded. There were legs where heads were supposed to be,” said Marko Cunningham, a New Zealand paramedic working with a Bangkok ambulance service, according to Reuters. “It was horrific.”

Security camera video showed the moment of the explosion: flames engulfing the blast site while onlookers ducked for cover or stood frozen in panic.

Somyos Pumpanmuang, the police chief, told reporters that the victims included tourists from China and the Philippines.

“Those who have planted this bomb are cruel,” he said, noting the timing and location of the attack. “Planting a bomb there means they want to see a lot of dead people.”

Some local reports, citing Thai police, placed the death toll as high as 27 but did not explain why the higher tallies differed from the official figures.

At least two Chinese nationals were killed, Beijing’s official Xinhua News Agency reported, citing the Chinese Embassy in Bangkok.

Thailand has faced a series of conflicts over the past decades, including the Muslim insurgency. Clashes between political factions also have spilled over into violence and major disruptions, such as occupations of Bangkok’s international airport.

The military has effectively ruled the country since May 2014, staging a coup after the elected prime minister was removed from office by the Constitutional Court. In April, Thailand’s military-backed government imposed tight rules on the size of public gatherings.

Defense Minister Prawit Wongsuwan said the blast appeared designed to undermine the country’s economy by striking “in the heart of the tourism district.”

The prime minister, Gen. Prayuth Chan-ocha said his government would set up a “war room” to coordinate its response to the attack.

In February, a series of small blasts targeted a shopping mall in Bangkok, leaving one person injured. In 2006, four people were killed in explosions in the southern tourist area of Hat Yai.

The Erawan Shrine was built in 1956 to appease spirits that Thai construction workers believed were causing deaths and otherwise hindering work on the adjacent Erawan Hotel (now the Grand Hyatt Erawan). It honors the four-faced Hindu god Brahma, a figure also revered by many Thai Buddhists.

The appeasement of the land spirits at the site was considered so successful that the shrine turned into a venue for worshipers, most of them Thai Buddhists but also including foreigners, to make ceremonial offerings in hopes that their wishes would be fulfilled. The shrine has long been crowded day and night with people making offerings amid wafting incense smoke and, sometimes, performances by Thai classical dancers. In 2006, a deranged Thai man attacked the Brahma statue with a hammer, smashing it to pieces. Outraged bystanders promptly beat him to death.

Murphy reported from Washington. William Branigin in Washington contributed to this report.

Read more:

Video footage and photos show deadly scene in Thai capital

Images from Thailand’s political battles

A coup and a king

Today’s coverage from Post correspondents around the world