Police are investigating a spate of robbery attacks on taxi drivers in Nottingham.
Nine drivers with local private hire firms have been targeted since the end of July, police said.
In several of the robberies, a fare calls the driver on a mobile and then climbs into the front seat of the taxi.
Several other people then get in the back, grab the driver and threaten him with a knife or screwdriver before stealing the night's takings.
Dead ends
Mobile phones and car keys belonging to the drivers have also been stolen.
Police say the gang is composed of both white and Asian men in their late teens and mid-20s.
The robberies have been committed mostly at the weekend in the early hours.
Sgt Leona Scurr said: "In all of these cases, the offender is not seen to come out of the house where the taxi has been ordered to go.
"The addresses have been checked and all of them are the homes of innocent people.
"Taxi drivers should take care when being called to pick up fares from dark dead-ends or cul-de-sac locations.
"Each driver targeted during these robberies has been put through a distressing experience. Some of them are even thinking twice about continuing to drive around the estates at night."