Blast, Gunshots Heard At American University In Kabul, Reporter Says

KABUL (CNN) -- One guard was killed and 21 students were injured Wednesday in an attack on the American University of Afghanistan in Kabul, said the head of Kabul Hospitals.

Eyewitnesses said they heard gunshots and a blast, while Tarek Mahjari, a reporter for TOLOnews, told his employer in a phone interview that fires are burning on the campus.

Ambulances, security forces and search and rescue teams are en route to the university.

A police operation is set to begin to search for any attackers on the property, according to Interior Ministry spokesman Siddiq Siddiqui.

The blast occurred at 7:50 p.m. local time when students were gathering and eating together.

Officials told CNN that it is too early for them to comment.

The report comes fewer than three weeks after the school was forced to suspend campus operations after two teachers -- an American and Australian -- were kidnapped at gunpoint. Their whereabouts remain unknown.

A rash of kidnappings and Taliban bombings have heightened security fears in Kabul. US and other diplomats have been barred from traveling by road the short distance from the city's international airport to their diplomatic missions. Instead, they've been ferried by helicopter.

Many countries, including the United States and United Kingdom, have longstanding travel advisories against all but essential travel to Afghanistan due to the security situation.

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