Several gunmen in plainclothes barged into the Karachi Press Club (KPC), searched the building and harassed reporters there, a Club official said on Friday.
"Dozens of gunmen in plainclothes entered the Karachi Press Club at 10.30 p.m. and harassed journalists, examined different rooms, kitchen, upper floor of the building and sports hall," Niamat Khan, Joint Secretary of the club, told Efe news.
"They forcibly made videos and took pictures with mobile cameras of different portions of the club. It caused panic amongst the journalists," he added.
Khan said when the journalists asked the raiders who they were, they were "not able to give satisfactory answers and why they were doing that".
The men arrived in several vehicles, including a police mobile, Khan said, adding that authorities have promised to investigate the incident.
"It is the first ever incident of this kind since the press club was founded in 1958," he said.
Pakistan is considered one of the most dangerous countries for journalists and Reporters Without Borders ranked it 139 out of 180 in the World Press Freedom Index.
In recent months, journalists in the country have organised protests against censorship.
In October, hundreds of journalists protested in Islamabad against censorship and restrictions against the media.
Journalists also voiced the lack of freedom to report before the July 25 general elections when English-language daily Dawn ran into circulation issues in parts of the country and television channel Geo was blocked in April.