A blast followed by gunfire were heard near the main university in the Afghan capital on Monday and security forces had been deployed to the area, the interior ministry said.
"Gunshots still can be heard in the area but security forces have blocked it of," Ministry of Interior spokesman Tariq Arian said.
"We don't know whether we are dealing with a coordinated attack or something else," he said.It was not clear if anyone had been killed or wounded or who was responsible.
The insurgent Taliban denied involvement in the attack, which comes at a sensitive time with persistent violence even as peace negotiators meet in Qatar to try to broker a deal between the militants and the government while the United States withdraws its troops.