A car bomb near a bus stop in central Istanbul, Turkey killed 11 and injured at least 36 on Tuesday. The Turkish police detained four suspects in connection with the bombing.

According to the state-run TRT television, a remote-controlled bomb planted inside a car went off as a service shuttle carrying police officers passed the said car in Turkey’s Beyazit district, which is close to a number of tourist spots. Of the 11 people killed in the blast, seven were police officers, Istanbul’s Governor Vasip Sahin said.

The four persons detained reportedly detonated that bomb using a remote-controlled device. The suspects are currently being interrogated at the police headquarters in Istanbul. According to a local news agency, Dogan, the car was rented by the suspects.

President Recep Tayyip Erdogan said the outlawed Kurdistan Workers’ Party (PKK) could be behind the attack, though no terror group has immediately claimed responsibility for the blast. The president, while visiting the injured at a hospital, said that such attacks are not new for the Kurdish militia PKK.

“We will fight against terrorists relentlessly to the end,” the ABC quoted him as saying.

Images of the street where the blast took place showed shattered storefronts due to the impact of the blast. Ambulance and fire engines were immediately sent to the spot following the blasts. According to a local news agency, gunshots were also heard after the blast, the DW reported.

German Chancellor Angela Merkel condemned the attacks and extended support to Turkey. “When it comes to the fight against terrorism, Germany is on Turkey’s side,” she said on said on Tuesday.

The foreign ministry of Germany also expressed solidarity for the victims of the attacks in tweets.

“We condemn the brutal attack in Istanbul and mourn with Turkey and with the dead. Our thoughts are with the relatives of the victims,” the ministry wrote on Twitter as quoted by the DW.