Torrential rain and thunderstorms hit Istanbul and surrounding regions late Saturday night and continued Sunday.
The heavy shower inundated many streets and some low-lying areas in Turkey's largest metropolis.
Traffic in the city moved slower than usual due to the adverse conditions Sunday, while people in the street took shelter at bus stops.
Istanbul's Esenyurt, Beykoz, Üsküdar, Ümraniye, Sarıyer, Şile, Beşiktaş, Kağıthane, Şişli, Zeytinburnu, Bağcılar and Fatih districts were among the worst-hit districts in the city.
Parts of the Haramidere stream in Istanbul's Esenyurt district flooded the surrounding area due to heavy rainfall.
While houses and workplaces on the riverside were flooded, the police, fire department, 112 Emergency Services and teams from Esenyurt Municipality were carrying out search and rescue operations in the area.
The flood water closed down 19 Mayıs Boulevard and nearby streets to traffic and pedestrians. It also inundated the ground floor of a local mosque, trapping worshippers and people sheltering there from rising water. They were later evacuated by search and rescue teams.
The Turkish State Meteorological Service (TSMS) had earlier warned of strong showers and thunderstorms for the Marmara region.
The capital Ankara was also hit by a severe downpour on Saturday night, according to reports.
Drivers and commuters were left stranded at several locations in the city after the rain submerged the streets.