The site of a deadly crowd crush in Itaewon, Seoul, is cordoned off, Oct. 31. Yonhap

Police investigating the deadly Halloween crowd crush in Itaewon are analyzing scores of witness accounts and security camera footage to determine the cause of the accident, a top police official said Monday.

The crowd crush in a narrow, sloped alley in the popular nightlife district in Seoul on Saturday night left 154 people dead and 149 others injured, 33 of them seriously.

"We have formed a 475-member special investigative team and are closely checking the circumstances of the accident by investigating eyewitnesses and analyzing CCTV video footage," Nam Gu-jun, chief of the National Office of Investigation, told reporters.

The team interviewed 44 eyewitnesses Sunday and has secured 52 pieces of surveillance camera footage in 42 places around the scene, he said. They also examining videos posted on social media sites.