An explosion early on Friday hit a Moscow State University hall of residence, next to landmark Stalin-era skyscraper, damaging a wall and smashing windows but causing no injuries.
An emergencies ministry spokesman Yevgeny Bobylov said: "The blast damaged a 3-sm section of an inner wall and smashed windows between the 10th and 14th floors."
He said about 1,200 residents have been evacuated from the 19-storey sector B of the university's main building.
No fire broke out following the explosion, and the university continues to function as normal, he said.
Bomb disposal experts from the interior ministry are working at the scene to identify the explosive device that went off on a staircase in the residence, said the spokesman. The cause of the blast is still being investigated.
The university experienced a similar attack last November, when a homemade bomb planted in the corridor of a hall of residence went off, slightly injuring one person.
The power of the explosion was estimated at 50 grams of TNT equivalent.