Masterton police are confident they have calmed down gang tensions in the town after a woman was seriously injured in an altercation on Sunday.

The woman was air-lifted to Wellington Hospital after two cars collided in Miriam Street, around 5pm.

She's in intensive care, in a stable condition.

Senior Sergeant Jymahl Glassey says extra police were sent from Wellington to Masterton to help calm the volatile scene.

He says it took them a couple of hours to get the situation under control.