The workers using oxygen tanks took refuge in an air pocket until rescue crews reached them.
The accident occurred shortly after 3 p.m. At 8:15 p.m., live television footage showed a train emerging from the tunnel and all 34 workers stepping from it. Three workers were put on stretchers by waiting emergency teams, though none appeared to have serious injuries.
Rafael Caro, spokesman for Gestor de Infraestructuras Ferroviarias, the company building the tunnel, said the workers were some two miles inside the tunnel when a train removing construction material caught fire near the entrance.
The train driver and several other workers managed to get out first, Caro said.
The rail line is to connect Madrid and the northern city of Valladolid. The accident occurred about 60 miles north of Madrid between the towns of La Granja and Riofrio.
Two parallel tunnels, each 19 miles long, are to be completed by early 2005 in the area. So far the crew has dug nearly two miles into one of the Guadarrama mountains.
It was the second serious accident along this stretch of the Madrid-Valladolid line this year. On January 20, two workers died when large gravel chutes collapsed on them.
Six other workers have died in other parts of Spain in recent years in construction of bullet-train lines, five of them on the line to link Madrid with Barcelona.
Spain has one running high-speed line, between Madrid and Seville.
