At least four persons, including two attackers, were killed and 20 injured in an attack on a television station here on Tuesday.The incident occurred in the morning after two terrorists, disguised as police officers, attacked Shamshad TV, a private Pashto language channel, in Chaman-e-Huzuri neighbourhood. The attackers lobbed grenades before storming the building, the Afghan media reported.The Islamic State through its Amaq News Agency said it carried out the attack in which a security guard, a female worker of the TV station and two attackers were killed, Tolo News reported.Afghan special forces had to blast their way through a concrete wall protecting the station to enter the site. The assault ended after a three-hour shootout inside the Shamshad TV building. The TV station's news director Abid Ehsas said the staff had been in their offices when the attackers entered the building wearing police uniforms. "They threw hand grenades at our security guards." The attackers then stormed news offices and started shooting at anyone in their sight, said Ehsas. He said most of the TV station's staff escaped, even by jumping out of the windows. "This is an attack on freedom of media but they cannot silence us," he said.Afghan President Ashraf Ghani and Afghan Journalists Safety Committee, an independent media safety group, strongly condemned the incident.Taliban spokesman Zabiullah Mujahid said on Twitter that the group was not involved in the attack.In May, a group of armed men attacked the National Radio Television station in Afghanistan's Jalalabad, the capital of the eastern Nangarhar province, during which the three attackers and two civilians were killed.A week ago, at least three people were killed in an attack in the diplomatic area of Kabul where several embassies and government offices are located.