It appears a sudden stop by an 18-wheeler truck set off the deadly multi-car pileup on the Cross Bronx Expressway.
It happened around 5:45 am on the eastbound side near Webster Avenue in Mount Hope.
According to police, a pick-up truck traveling behind the 18-wheeler hit the breaks to avoid an accident only to be slammed by a tractor-trailer behind it.
The pick-up ended up wedged underneath the larger truck.
Another car was hit in the chain reaction and it came to a stop on top of the center divider.
Three of the five men inside the pickup died.
The other two were seriously injured.
The drivers and passengers of the other vehicles suffered minor injuries.
Investigators are looking into what caused the first truck to make its sudden stop.