Ontario's Special Investigations Unit returned Wednesday to the scene of a collision that happened on Sunday involving an OPP cruiser and a taxi.

Porsche Clark, 27, and her daughter, nine-year-old Skyla, remain in hospital in critical condition following the crash. The taxi driver was treated in hospital and released.

A mobile command post was set up at the No Frills grocery store at the intersection of Southdale Road East and Verulam Street.

Investigators were hoping to speak to anyone who may have witnessed the crash or the police pursuit that led to the incident.

The doors to the mobile unit were closed, and there appeared to be minimal activity, but a small number of people were seen coming and going including both investigators and civillians.

An SIU investigator on scene declined to comment or make any kind of statement about what they’re up to.

The Sunday crash followed a bank robbery in Sarnia and a police pursuit that led all the way to south London.

Two Missisauga-area men are facing numerous charges in connection with the robbery in Sarnia, though no charges have been laid by London police.