Turkish authorities detained more than 300 people during overnight protests in more than a dozen cities against the arrest of Istanbul Mayor Ekrem İmamoğlu. The Interior Ministry said today that arrests were made in Turkey’s largest city, Istanbul, the capital, Ankara, as well as in İzmir, Adana, Antalya, Konya, and several others.

According to media reports, tens of thousands of people have taken to the streets in mostly peaceful demonstrations since Wednesday, when İmamoğlu was arrested over alleged links to corruption and terrorism. It said that demonstrations have been held in at least 55 of Turkey’s 81 provinces so far. Istanbul Mayor Ekrem İmamoğlu is a popular opposition figure and is seen as a top challenger to Erdoğan.