The road is shut both ways from A141 March Road (Guyhirn Roundabout) to the Parsons Drove turnoff.
A Cambridgeshire police spokesman said: "There are three vehicles involved and damaged – a Ford, a Vauxhall van and a Honda.
"There are some injuries but none are life threatening.
"It happened about 7.30am and ambulance called but it is not clear whether anyone has been taken to hospital.
"We would appeal for anyone who saw what happened to call us on 101 or on web chat and quote incident 80."