Police boosted security across Bangladesh on Tuesday fearing violent protests after ex-Prime Minister Sheikh Hasina was arrested on extortion charges on Monday.

Three small homemade bombs exploded at a university campus in the capital, but no one was hurt, university official A K Feroz said.

Police were investigating the bombs—small tin pots filled with explosives—at Dhaka University and it was unclear whether they were related to Hasina’s arrest, Feroz said.

Riot police used batons and rubber bullets to disperse Hasina’s supporters in Dhaka on Monday after she was arrested at her home, under the military-backed government’s anti-corruption drive, said Motia Chowdhury, a leader of Hasina’s Awami League.

At least 12 protesters were detained and several demonstrators injured, Chowdhury said.

“We have asked the security forces to remain alert against any violence,” a police official said on Tuesday .

Hasina (59), who was prime minister from 1996 to 2001, was denied bail on Monday and ordered held in jail until her trial.

Awami League spokesperson Zillur Rahman condemned the arrest as politically motivated, and groups representing lawyers, teachers and politicians urged the government to free her.

“The arrest of Sheikh Hasina is a shameful incident,” lawyers in the Supreme Court Bar Association said in a statement Tuesday. Teachers at Dhaka University and members of several small political parties issued similar statements.