A four-year-old girl was air-lifted to hospital in London with life-threatening injuries Thursday.

She was in a minivan that crashed in Chatham-Kent.

Police say it happened on Bloomfield Road at 8th Line just before 9 a.m.

Police allege the minivan ran a stop sign, went airborne and hit a guard rail and tree.

The child's mother was driving, and her eight-year-old sister was also in the vehicle, police said.

Both of them are being treated at the Chatham hospital.

Police want to hear from anyone who witnessed the crash.