The deputy mayor of the town, Antonia Bauza, confirmed to Cadena SER radio that two of the victims were British, while two others killed in the town were locals.
Two British nationals are among the victims of a devastating flood that hit the popular tourist island of Majorca overnight.
Deaths as "catastrophic" storm hits holiday island.
The Britons, who were married and in their seventies, were travelling by taxi about 40 miles east of the Spanish island's capital, Palma, when the vehicle was swept away.
Pedro Sanchez, who had been filming a swollen river with his mobile phone, said he escaped through the window of his auto and swam to safety after the waters rose two metres in 30 seconds, engulfing his vehicle.
People walk along the damaged waterfront after a storm on the island of Mallorca, Spain, on October 10, 2018.
Spanish tennis star Rafael Nadal, who is from Mallorca, helped residents clear mud from their houses in Sant Llorenc.
Witnesses described having minutes to find safety as the water levels rose, inundating houses and catching motorists off guard.
Spanish authorities said 80 soldiers would join more than 100 rescuers working in the area.
He said: "My solidarity and support goes out to the families and friends of victims and all the affected by these tragic floods". "We had to swim to try to survive".
At least three towns closed schools and hundreds of people were sheltered in sport facilities and a local horse racing track. The flooding also affected phone communications and forced the closure of at least seven major roads.
Dramatic video footage on social media shows raging torrents of water gushing through the streets of the town, with reports that more than 20 centimetres of rain fell in just four hours.
The weather agency, AEMET, said more heavy rainfall is expected Wednesday in eastern and southern parts of the Iberian peninsula.
Lawmakers held a minute's silence before the weekly prime minister's question time on Wednesday morning.