UPDATE, MAY 26, 12:15 p.m.: Cal/OSHA and a City of Oakland building engineer were on-site following the incident. Cal/OSHA will be investigating the incident focusing on where the collapse took place. Construction has been halted for the day.

Construction workers were injured Friday at an Oakland construction site following the partial collapse of a building under construction at 3093 Broadway. Thirteen workers were temporarily trapped in wet concrete and under debris, the San Francisco Chronicle reports. Some workers escaped on their own, and some sustained bruises and scrapes. No injuries were life-threatening.

All workers have been accounted for and some were sent to local hospitals as a precaution, according to the Chronicle. The cause of the partial collapse of the second floor is unknown. Workers were pouring cement on the second floor when the structure collapsed, according to Oakland Fire Battalion Chief Ian McWhorter.

The development is along Auto Row at the site of a former Chevy dealership. The site is being developed by CityView into a seven-story building with more than 420 apartments, 24K SF of retail, a restaurant, 472 parking spots and 266 bike parking spots. The project is expected to deliver early 2018. The contractor is Johnstone Moyer, which has had 11 minor cases investigated by Cal-OSHA over the past few years, mostly related to permit problems, according to KTVU.