Kenyan authorities said they secured a university campus in eastern Kenya and were trying to drive out suspected Islamist militants who stormed the facility and took students hostage.

An unknown number of heavily-armed assailants forced their way into Garissa University at about 5:30 a.m. on Thursday, shooting at guards manning the main gate, police Inspector General Joseph Boinett said in an e-mailed statement. Police officers protecting student accommodation engaged the gunmen, who retreated and gained entry to the hostels, he said. The campus is located in Garissa town about 228 miles (367 kilometers) east of Kenya’s capital, Nairobi.

“They stormed the hostel immediately after Muslim morning prayers and fired indiscriminately at students who were fleeing,” county police commander Charles Kinyua said by phone.

Other students remain in the building and security forces and Kenyan troops are exchanging gunfire with the assailants, who authorities suspect belong to the al-Shabaab militant group, Kinyua said. Kenya’s Interior Ministry said on its Twitter account that police were flushing out the gunmen.

Kenya’s state-run National Disaster Operation Centre said on its Twitter account that two people were killed, while Kenya Red Cross said 30 casualties had been taken to hospital, four of them in serious condition. Kinyua said he didn’t yet have casualty numbers.

Attacks in Kenya soared after the government in 2011 sent troops into neighboring Somalia to fight al-Shabaab following a wave of kidnappings and the murder of a British tourist in Kenya that the government blamed on the group.

Assault Rifles

One student who fled, Njeri Maina, said three assailants entered the university’s main accommodation building carrying assault rifles and grenades. They shouted in Arabic, then Swahili, telling everybody to lie down before they opened fire, she said by phone.

“I managed to lock myself in a nearby toilet and leave the building through the back entrance after security forces started engaging the attackers,” Maina said.

Al-Shabaab has waged an insurgency in Somalia since 2006 in a bid to impose Islamic law. In September 2013, the al-Qaeda-linked militia claimed responsibility for an attack on the Westgate mall in Nairobi that left 67 people dead and the country has faced bombings of bars, churches, and markets.