Turkey ? Turkish authorities captured a gunman Thursday wanted in the deadly attack on the U.S. consulate after rounding up suspects who had communicated with three other assailants killed by police, local media reports said.

Officials were investigating whether the attackers were linked to al-Qaida. Police suspect the four gunmen had ties to the terrorist network but said that so far they had no proof of that link.

Wednesday’s attack on the consulate in Istanbul ignited a firefight that killed three policemen and three assailants and prompted Turkey to increase security at all U.S. diplomatic missions in the country.

The private Dogan news agency reported that the fourth gunman, who fled after the attack, was caught after his getaway car was found Thursday and was being interrogated. A police officer in Istanbul confirmed the report but would not give details. He refused to give his name because Turkish law bars civil servants from speaking to journalists without authorization.

Interior Minister Besir Atalay earlier said police detained four others suspected of links to the gunmen hours after shootout.