Video footage circulating on social media appears to show passengers in life jackets sitting on the overturned ship as they wait to be reached.
Seven people have reportedly died after a passenger ship capsized off the coast of northern Cyprus on Sunday.
The vessel, which was reportedly sailing from Kyreneia in Cyprus to the Turkish port of Taşucu, sank at around midday.
Turkey's Interior Ministry said 259 passengers and eight crew members were on board the vessel when it began taking on water roughly 6 km off the coast of Kyreneia.
Murat Senkul, the mayor of Kyreneia, described the situation as "very serious" in a post on Facebook, adding that a rescue operation was under way.
Speaking to CNN Turk, Tufan Erhürman, the president of the self-declared Turkish Republic of Northern Cyprus, said: "So far, we have reached 244 people. Seven of those reached have lost their lives, and 23 people are missing."
Video footage circulating on social media appears to show passengers in life jackets sitting on the overturned ship as they wait to be reached.
The cause of the incident is not yet clear.
Cypriot President Nikos Christodoulides' office said in statement on the sinking: “Our position is clear: when human lives are at risk, we contribute with every available means."
"The Republic of Cyprus has the resources, the operational capacity, and, above all, the readiness to provide immediate assistance," it added.
Cyprus has been divided since 1974, when a Greek-backed military coup led to an invasion by Turkish forces and the division of the island.
This is a developing story. Check back for further details.