The parents and their children - believed to be from the West Lothian area - died after their Fiat collided with an aggregates lorry on the A801 near Polmont yesterday afternoon.
The road was closed as emergency services began an investigation.
One person was cut free from the crash by firefighters.
The accident happened at around 2.20pm near the Lathallan roundabout by junction four of the M9.
The A801 links the M8 and M9 and has been the scene of numerous accidents.
Last night police stood guarding the scene as an investigation was launched.
A spokesman for Police Scotland's East division said that there had been "a number" of fatalities.