PALMA, Spain, May 24, 2024 (BSS/AFP) - Spanish fire crews picked through the wreckage of a beachfront restaurant on the holiday island of Mallorca on Friday, searching for clues after it partially collapsed, killing four people and injuring 16.

Authorities, who declared three days of mourning, gave no immediate indication of the cause but a fire official said the "excessive weight" of a crowd in the building was most likely to blame.

The packed two-storey building collapsed late on Thursday afternoon in the Playa de Palma area south of the capital with the tourist season already in full swing in the Balearic Islands, which also includes Ibiza and Menorca.

Those killed are two German women, aged 20 and 30, a 44-year-old Senegalese man and a 23-year-old Spanish woman who worked at the venue, a police spokesman said.

Palma deputy mayor Javi Bonet said the two Germans were on holiday while local media said the Senegalese man had lived on the island for years.

Sixteen people were injured, an emergency services spokeswoman said.

Seven people were injured "very seriously" and nine were "seriously" injured, emergency services said on X (formally known as Twitter).

They were taken to various hospitals in the Mediterranean island's capital, Palma de Mallorca.

Firefighters were deployed in numbers, ambulances rushed victims to hospital and the street was sealed off by police to allow rescue teams to work, an AFP journalist saw.

- 'Screaming, crying, hysterics' -

The building housing the Medusa Beach Club is made up of a restaurant and bar with a rooftop terrace and a basement located in a busy tourist area.

A technical team was at the site on Friday to determine the cause of the collapse of the building, which sits on Calle de Cartago facing the Bay of Palma.

The head of the Palma fire service, Eder Garcia, said the street-level floor of the building had collapsed onto a bar in the basement, which is "where we found the most victims".

"The causes are being investigated. The first hypothesis is that it was possibly due to excessive weight," he told reporters at the scene.

Most of the victims are foreigners, Garcia said.

Santiago Aranga, an area resident who was walking his dog on the sidewalk across the street from the venue at the time, said he heard a "boom" that sounded "like a bomb".

"There was screaming, crying, hysterics," he told local television station TRECE.

Most people in the area were German tourists and "it was very difficult to try to calm them down, to pull people out in another language. I don't understand or speak German," he added.

- 'A Lot of commotion' -

Another local resident, Vicky Garcia, said the venue had only recently reopened after having undergone a refurbishment.

"We heard a roar, then a lot of police, a lot of firemen, a lot of commotion," she told local television IB3.

Spanish Prime Minister Pedro Sanchez conveyed his condolences to the victims' families on X, saying he was "closely following the consequences of the terrible collapse".

The central government was prepared to send "all the necessary resources" to help the regional authorities cope, he added.

Balearic Islands president Marga Prohens said on X that she was "shocked" by the news, adding she was sending "love and warmth to the families of the four people who have lost their lives".

Mallorca is known for its pristine waters and beaches, and the Balearic Islands attract more tourists than all Spanish regions after Catalonia.

More than 14 million tourists visited the islands last year, according to official figures.

Thursday's collapse took place at the start of the archipelago's peak tourist season, on a beachfront avenue home to several shops and entertainment venues.

The 2009 collapse of a three-story building in Palma de Mallorca killed seven people, including three Colombians and two Germans.