While three were killed on the spot, two others, including the child, were rushed to a hospital, where they were declared brought dead, railway sources said.
The car driver was identified as Sumesh (26) and the others as Karthikeyan, Naryananan Chellappan and Nelfin, the child.
Expressing sorrow and shock at the accident, state Transport Minister Aryadan Mohamed stressed the need to set up manned level crossings, which should be taken up with the Centre.
Though this issue has been brought to the notice of the Centre several times, no solution has been found, he said.
The minister also wanted Railways to provide adequate compensation to the families of the victims and said the state would also extend immediate relief to them.
The Kochi-Alappuzha stretch has a string of unmanned level crossings, where several accidents have occurred in the past.
In 2010, four tourists, including a foreign couple, were killed when their car was hit by a train at an unmanned level crossing at nearby Mararikkulam.
