The death toll from a gas train explosion in a seaside town in Tuscany, Italy, has climbed to 22, authorities said.

A 40-year-old woman and two other burn victims died Friday, and four people remained in critical condition, ANSA reported. Some victims haven't been identified because they suffered such severe burns, the BBC said.

The train jumped the tracks and exploded Monday night as it passed through Viareggio, engulfing homes in flames.

The national cabinet declared the scene, which includes a neighborhood along the tracks, a national disaster area Friday. The designation remains in effect until Dec. 31 and government funds will be allocated for recovery.

The railroad station in Viareggio partially reopened three days after the blast but officials said they believe delays and cancellations would continue for a few more days. Viareggio is a hub on the rail line, which runs along the west coast of the country.

National officials told ANSA, the Italian news agency, a national day of mourning would be declared.