A female suicide bomber blew herself up Tuesday in an attack on a police station in Istanbul’s historic Sultanahmet district. The explosion killed one police officer and wounded another, reported Reuters.

The woman entered the police station and told officers that she had lost her wallet, before detonating the bomb, said Vasip Sahin, the city’s governor. He noted the woman spoke English with “a thick accent,” though her nationality and identity remain unknown, reported the BBC. Police have since sealed off an area within the historic district, where sites like the Hagia Sofia museum and the Blue Mosque are located. No group has yet claimed responsibility for the attack.

The attack is the second on police in the Turkish capital in the past week. On Thursday, authorities arrested an armed man after he tried to attack a palace complex near Prime Minister Ahmet Davutoglu’s office in Istanbul. The man, later confirmed to be a member of the Revolutionary People's Liberation Party-Front (DHKP-C) organization, threw two homemade grenades at police in front of the Dolmavahce Palace, according to the New York Times.

The DHKP-C, a radical Marxist group, is considered a terrorist organization by Turkey, the United States and the European Union, and has carried out a number of sometimes deadly attacks in Turkey and abroad over the last years, reported Agence France-Presse. It was also behind the February 2013 suicide bombing at the U.S. embassy in Ankara that left a security guard dead.

Public transport resumed in Istanbul following Tuesday’s attack after briefly being shut down. Despite the incident and the heavy snow that hit Istanbul, tourists have been seen walking around Sultanahmet Square, reported Sky News. The historic district is one of the world’s most visited tourist destinations.