ISLAMABAD, Pakistan — Unidentified gunmen opened fire on the office of a leading news media group in Karachi on Monday evening, wounding a security guard and underscoring the threats journalists face in the country.

The motive of the attack, on the offices of the Express Media Group, remained unclear, and there was no immediate claim of responsibility.

Pakistan is one of the world’s most dangerous countries for journalists, who face frequent harassment and intimidation here from a variety of groups, including the Pakistani Taliban and other militants, state security forces and intelligence agencies, and local political and criminal groups. So far this year, at least five journalists have been killed. And 44 more have been killed over the past decade, according to the New York-based Committee to Protect Journalists.

The Express Media Group publishes an Urdu-language newspaper and an English daily, The Express Tribune, which is a partner publication of The International New York Times. The group also owns the Urdu television network Express News.