ISTANBUL (AP) — An earthquake measuring magnitude 4.2 hit near Istanbul on Thursday, a Turkish government agency reported, causing some residents to rush outdoors in fear. There was no immediate report of damage or casualties.

The Disaster and Emergency Management Presidency said the quake was centered in the Sea of Marmara, off the town of Marmaraereglisi. It struck at 04:38 pm (13:38 GMT) and was felt in Istanbul, a city of more than 15 million, and other regions.

Many people poured out of their homes or offices, the state-run Anadolu Agency reported but the Istanbul governor’s office said: “no negative developments have been reported so far.”

Turkey is crossed by fault lines and is prone to earthquakes. In 1999, two major earthquakes hit northwestern Turkey, killing some 18,000 people.