Four construction workers were injured, two of them seriously, when a brick exterior wall at a school in Montreal collapsed Wednesday. Quebec provincial officials said the four men had put up scaffolding and just begun repairs to the wall at the school in Ville-Emard neighborhood when it suddenly fell on them at 7:30 a.m., local media reported. One orker is in critical condition with head and internal injuries at the Montreal General Hospital. A second suffered a head injury and is listed in stable condition, while the other two men are being treated for trauma. Provincial workplace health and safety officials are investigating the accident at the school, where students are still on summer vacation. 