McCormick said the collision was “a tragic reminder of the importance of safety on our roads”.
The number of serious and fatal collisions in Bolton had “massively reduced…but we’ve all got much more to do,” she added.
“One incident is one too many and they’ll do nothing to bring back the four lives lost here today.”
The casualties have yet to be formally identified.
Councillor Ayyub Patel, who represents the local ward of Rumworth, told BBC Radio Manchester that the victims’ relatives were “devastated”.
“The community was waking up to this very sad news, they are shocked – the mood is sombre.
“Any loss of life in any family is devastating news and to wake up to such tragic news is more so than expected.
“If it’s expected, you know what’s coming but if it’s not expected, then obviously it’s a shocking experience.”