Athens, Greece - Flash floods have killed at least 11 people in the western outskirts of the Greek capital, Athens, as rescue teams are still searching for missing individuals.

The deaths on Wednesday took place in the Mandra, Nea Peramos and Magoula areas, while authorities in the town of Megara said they were searching for several missing residents.

"We have had hundreds of calls for help," Stavros Fotiou, the vice mayor of Megara, told Al Jazeera by telephone.

"We are trying to access some areas and open the roads, but the rain still hasn't stopped," he added.

Fotiou could not yet confirm the number of damaged houses and vehicles, but said local municipal authorities were working with the fire department to help people who were displaced.

Yiannis Kemmos, a local reporter who was on the scene of the floods, said there "was a lot of panic during the heaviest rains".

"Many cars were destroyed or damaged in the streets, and a lot of people are outside because their homes were flooded," he told Al Jazeera by telephone.

"People are waiting for help, but most don't seem to be in immediate danger anymore."

Prime Minister Alexis Tsipras said in a post on Twitter he was "deeply saddened" by the loss of life caused by "the catastrophic storm".

He said a government team had been dispatched to the area to coordinate with local authorities about rescue operations and relief efforts.

Nikos Voutsis, president of the Greek parliament, released a statement expressing his condolences for the families of the victims.

According to Greek media, the heavy rains were expected to continue throughout the evening.