Medics have rushed three people to hospital after a bin lorry overturned in wind, the ambulance service said.
Two people in the bin lorry were cut out by firefighters in the crash between Junction 11 for Fareham and 12 for Portsmouth.
Police have said partial road closures may be in place for up to seven hours.
Delays are expected of around an hour.
Hampshire Fire and Rescue Service said the lorry had jack-knifed.
A South Central Ambulance Service spokesman said: “It’s a rubbish lorry that overturned, possibly due to wind.
“There were three patients inside the vehicle.”
Three ambulances attended along with the hazard area response team and rapid response vehicles.
The air ambulance was called but was not used to transport patients.
A Highways England spokesman said: “There’s 20 metres of double-sided road barrier damaged.”
He added drivers are advised to use the A27 to avoid the motorway. Repairs are set to take several hours.