Just after 11pm on Thursday, 15 October 2020 police were called to licenced premises in Throssell Street, Collie.
Police were responding to reports of a traffic crash involving pedestrians as well as a possible wall collapse.
Two women, 18 and 23 years were injured in the incident.
The 23-year-old woman was flown to Royal Perth Hospital in critical condition.
The 18-year-old woman was conveyed to Collie Hospital in a serious condition.
A man is assisting police with their inquiries.
Police have closed Throssell Street in Collie, between Mungalup Road and Steere Street South, as investigations continue.
Anyone who witnessed the incident is asked to call Crime Stoppers on 1800 333 000 or report online at www.crimestopperswa.com.au.