(CNN) — At least 146 people are now reported to have been killed during an incident at Halloween festivities in Seoul’s Itaewon neighborhood Saturday night, according to Choi Seong-bum, chief of the Yongsan-gu Fire Department.

At least 150 others were also reported injured, the chief added.

The cause of the deaths has not been confirmed, but the fire chief said many people fell during the Halloween festivities, resulting in casualties. The chief said they received reports of people “buried” in crowds starting around 10:24 p.m. local time Saturday night.

Earlier, the Yonhap News Agency reported that some people had suffered from “cardiac arrest,” attributing the statement to fire authorities. Emergency officials assisted at least 81 people in Seoul’s Itaewon neighborhood reporting “difficulty breathing.”

Dozens of the injured were transferred to nearby hospitals, said Choi Jae-won, the head of Yongsan Health Center, adding that the death toll would likely increase.

Authorities are still investigating what caused the incident; there was no gas leak nor fire on site, according to the fire chief.

A witness described a chaotic scene to CNN, saying he saw people jammed in a narrow street unable to breathe.

“I saw people going to the left side and I saw the person getting to the opposite side. So, the person in the middle got jammed, so they had no way to communicate, they could not breathe,” Song Sehyun told CNN.

Police closed off the area and social media videos showed people lying in the streets and on stretchers as first responders rendered aid.

The fire chief said that a total of 848 emergency response forces have been dispatched, including 364 firefighters and 400 police officials.

South Korean President Yoon Suk Yeol sent a disaster medical assistance team to the Halloween incident, according to the presidential office.

The president also ordered authorities to secure emergency beds in hospitals nearby and to implement swift rescue operations and treatment, presidential spokesman Lee Jae-Myung said in a briefing.

Yoon was in an emergency meeting regarding the situation, the office said in a statement.