Three people were killed and another was seriously injured when they were run over by a train in southwest France on Tuesday morning, local media reported.

France's national railway company SNCF confirmed to RTL news that three people died on the spot and the fourth was seriously wounded in the lower limbs. The survivor, a 28-year-old male, was taken to the hospital.

The four are reportedly immigrants and were sleeping on the railway tracks at Saint-Jean-de-Luz in the Pyrénées-Atlantiques department when they were hit by the train at 5.30 a.m (0330GMT). A judicial investigation is underway and the exact identity of the victims is yet to be ascertained.

Eneko Aldana-Douat, mayor of Ciboure commune, adjoining the site of the accident, told BFMTV that the area close to the Spanish border is one of the important crossing routes for migrants and asylum seekers. He added that usually the migrants are found around the railways, the sides of the highways and the cross-country bridge from Irun in Spain to Hendaye in France.

According to NGOs working with refugees, asylum seekers are caught in a dangerous hide and seek cycle with the French and Spanish authorities. The French police regularly round up asylum seekers and hand them to the Spanish police who release them back to enter France after conducting identity checks.