Offenders tried to drag a woman from a car while she sat waiting to collect her children from a nursery in Cheetham Hill.
Greater Manchester Police are appealing for information about the incident, which took place at 3.55pm on Thursday 20 September.
A woman in her 20s was waiting in a car outside the nursery on Tamerton Drive, when three men approached the driver’s door. One of them pulled a red wrench from inside his coat and smashed the window.
A second man produced a green-handled pen knife with a 4-inch silver blade and threatened to stab the woman, before reaching inside the car trying to drag her out.
She managed to fight back but a third man then reached inside the car and stole her phone.
They also stole a gold chain that was ripped from around the woman’s neck, before running into a nearby housing estate.
The offenders are described as white males, aged in their mid to late teens. They were all of slim build and were wearing black hooded tops, black trousers and gloves. All had their faces covered.
Detective Constable Dave Bennett from GMP’s City of Manchester Division said: “This was a shocking and violent attack on a woman who was simply waiting to collect her children.
“We are following several lines of enquiry in order to trace the offenders and would ask anyone with any information to contact police immediately.”