WorkSafe BC has launched an investigation following a serious accident at a Surrey construction site that sent three people to hospital.

The agency says building materials were being delivered by crane to a site at 152nd Street and 102 Avenue, just behind the Guildford Library, when material broke loose and struck three construction workers.

The incident happened around 10:30 a.m. Monday morning.

Two people are in critical condition at Royal Columbian Hospital and a third victim is in stable condition at Surrey Memorial Hospital.

Worksafe BC says two of the victims are employed by Viaduct, a contractor at the work site, and the third person works for Convoy Building Materials, the delivery company.

A prevention officer is now determining what led to the incident, including the crane condition or setup, or any training or supervision issues.

A crane specialist and engineer have been brought in to assist the investigation.

A total of 6,629 construction workers have reported being struck by objects on general work sites in the past five years in B.C.