South Korean President Yoon Suk-yeol on Monday opened a memorial to the 154 people killed in a stampede at Halloween celebrations, as authorities accused the disaster was caused by lax control measures.

After the President and his wife laid single white flowers at the huge altar erected in central Seoul for the victims – mostly young women – of Saturday’s disaster, the public began to arrive to pay their respects.

A man knelt before the black altar covered with neat rows of white flowers and wept.

People also stopped to pray and lay flowers at a makeshift memorial outside a subway station in the popular nightlife district of Itaewon, where the tragedy occurred.

Demands for accountability mounted in the press and online on Monday as potential crowd control and police failings surfaced.

Up to 100,000 people – mostly in their teens and 20s, many in Halloween costumes – had streamed down Itaewon’s small, winding streets, with eyewitnesses reporting little security and no crowd control.

Police said at a briefing on Monday they had deployed 137 officers to the event, noting that the number was significantly higher than in previous years.

However, according to local reports, most deployed police officers focused on drug use rather than crowd control.

“This was a disaster that could have been controlled or prevented,” Lee Young-ju, a professor in the Department of Fire and Disaster at Seoul University, told YTN.

“But that was not taken care of, nobody took responsibility.”

Claims also circulated online that police did not actively manage crowds this year, allowing too many people to gather around the subway station and in the alleys at the epicenter of the disaster.

“I’ve lived in Itaewon for 10 years and have seen Halloween every year, but yesterday wasn’t particularly crowded compared to previous years,” wrote Twitter user @isakchoi312.

“Ultimately, I think the root cause of the disaster was crowd control.”

The government also defended the police plan on Sunday.

“(The rush) was not a problem that could be solved in advance by deploying police or firefighters,” Interior Minister Lee Sang-min said at a briefing.

South Korea is typically strong at crowd control, with the country’s regular protest rallies often being so heavily policed ??that officers can outnumber those attending.

But protest organizers are required by law to report the plans to authorities in advance, but there were no such requirements for the young people who flocked to the Itaewon Halloween event.

Tens of thousands of partygoers were packed into the downhill alley, which was no more than three meters (10 feet) wide, with eyewitnesses describing scenes of chaos as people pushed and shoved to get through with no police in sight around them to lead or control the crowd.

Witnesses described being trapped in a narrow, sloping alley, struggling to get out of the suffocating crowd as people crowded one on top of the other.

Most of the 154 dead, including 26 foreign nationals, had been identified on Sunday, with the Education Ministry confirming on Monday that at least six young teenagers were among the victims.

But the toll could continue to rise with at least 33 people in critical condition, officials said.

The country began a week of national mourning, with entertainment events and concerts canceled and nationwide flags flying at half-mast.