Three explosions took place at Cairo University  on Wednesday morning, killing two people, including a policeman, and injuring five others.
A fourth device was deactivated.
Shortly before midday, two explosions took place near a police guard post outside the university, according to Hesham Youssef, the head of the explosives section at Giza security directorate.
At around one o'clock, a third bomb went off in a tree near the university's front gate.
They were detonated remotely, and police are searching the area for more devices, Youssef said.
Brigadier-General Tarek Al Mergawi was killed and five other policemen were injured.
Al Mergawi was the head of West Giza investigative police. 
The explosions caused part of a building to collapse, eyewitnesses said.
The university has been evacuated and the area cordoned off by police.
Fifteen students have been arrested in the vicinity of the university and taken to Giza security directorate for questioning, a police source told Ahram Online.
Universities have become a key venue for protests in support of deposed president Mohamed Morsi.
Clashes have frequently broken out between pro-Morsi students and security forces since the beginning of the new semester, which was delayed for three weeks due to security concerns.
Two students died in clashes between protesters and police earlier this week at Al Azhar University in Cairo. 
On 20 March, engineering students started a strike in protest at on-campus violence the day before, in which security forces clashed with pro-Brotherhood students.
Also on 20 March, explosives experts defused two bombs at the law faculty of Cairo University.