MADRID (Reuters) -An outdated terrace structure and excess weight likely caused the collapse of the Medusa Beach Club in Spain's Palma de Mallorca which killed four people, the fire chief said on Friday.

Two German tourists, a Spanish waitress and a Senegalese man were killed when the two-storey beachside restaurant building collapsed on Thursday, a spokesperson for the city council said.

"Investigations are still ongoing, but everything points to a combination of an outdated structure and overweight," Eder Garcia, the chief of Palma de Mallorca's fire department, told reporters.

The accident came as Spain's Mediterranean Balearic islands prepare for a summer tourism season expected to bring millions of visitors.

The German victims were two women aged 20 and 30, the waitress was 23 and the Senegalese man was 44, the council said in a statement.

All the 16 reported injured were Dutch tourists, the council spokesperson said. Eight were still in hospital on Friday and were all out of danger, Palma de Mallorca's mayor said.

A spokesperson for German's Foreign Ministry said its consulate in Mallorca was in close contact with authorities.

"The situation on the ground is still partly unclear," the spokesperson said. "At this point in time, we unfortunately have to assume that German nationals are among the dead and injured."

(Reporting by Inti Landauro, editing by Aislinn Laing and Nick Macfie)