Islamabad, Pakistan (CNN) -- A suicide attacker detonated a bomb at a club for journalists in the northwestern Pakistani city of Peshawar, killing at least four people Tuesday and injuring 17 others, a hospital official said.
The attacker tried to enter the landmark Peshawar Press Club at about noon local time when a policeman searched him and realized the bomber was rigged to detonate just before he pushed the button, according to Saleem Amanullah, head of the local police station.
The force of the blast shattered the window panes of the gated brick building.
Casualties were shuttled to Lady Reading Hospital, the city's largest medical facility. Hospital official Jamil Shah confirmed the four deaths, among them the policeman and the bomber.
Peshawar, the capital of Pakistan's Northwest Frontier Province, is situated on the road into Afghanistan and is considered by many to be at the core of Pakistan's war on terror. Local journalists said that the press club had received numerous threats from the Taliban.
"We were on full alert since about four months now and there were a 24-hour guard watch at the club," said Shamim Shahid, the president of the press club, before heading out to the funeral of the police constable who had stopped the suicide bomber.
"This was an unfortunate incident but it further strengthens our resolve," he added.
"It's pretty clearly an attack on local journalists along the borders with Pakistan and Afghanistan," said Bob Dietz, Asia program coordinator of the Committee to Protect Journalists. "They've been under fire for years. But there's never been this outright an attack on them in the past. This is clearly an escalation of the war against the media."
As the Pakistani military has launched multiple offensives targeting its own homegrown militants, the retaliation has been felt in Peshawar.
In October a truck bomb in a popular market killed over 100 people and government and security forces have suffered regular attacks.
CNN's Arwa Damon and journalists Umar Aziz Khan and Nasir Habib contributed to this report.