Al-Shabab gunmen have attacked a college campus in the town of Garissa in northeast Kenya, shooting indiscriminately in dormitories and killing at least two people and wounding 40 others, police said.

Witnesses said explosions and heavy gunfire rocked Garissa University College early on Thursday as the gunmen stormed the complex. Ambulances were seen driving injured students to local hospitals.

The gunmen were holding an "unknown number of student hostages," the Kenya Red Cross said in a statement. Some "50 students have been safely freed", the organisation said.

Terrified students streamed out of buildings, some young men shirtless, as arriving police officers hunkered down, taking cover, witnesses said.

Al-Shabab claims attack

Somalia's al-Qaeda-linked al-Shabab group claimed responsibility for the attack, saying it was revenge for Nairobi's troops fighting in Somalia.

"Kenya is at war with Somalia … our people are still there, they are fighting and their mission is to kill those who are against the Shabab," rebel spokesman Sheikh Ali Mohamud Rage told AFP news agency by telephone.

The gunmen opened fire at university, triggering a "fierce shootout" with police guarding student dorms, Kenya's National Police Service said in a written statement.

Police spokesperson Zipporah Mboroki told Al Jazeera that the situation is ongoing and that the gunmen were holed up inside the university complex.

"The attackers shot the guards at the entrance of the university. Police officers responded but the attackers managed to get into the [university] hostel," she said.

"We can confirm that two watchmen were killed; we cannot confirm student casualties," Mboroki added.

Local journalists, however, reported that at least 10 bodies were brought to a hospital in Garissa. Another 40 people were reported injured.

"The Kenyan Defence Force (KDF) and all security agencies within Garissa have been deployed to the scene," Mboroki said.

The attack on the university facility began at dawn, Alinoor Moulid, a freelance journalist based in Garissa, told Al Jazeera.

"According to some of the students who escaped, there are around five gunmen and they entered the university dormitory while students were sleeping," Moulid said.

"It is hard to tell [about casualties] because the area is now cordoned off, and it is heavily guarded," he added. "At the moment, I can hear sirens, and at some point I could hear an exchange of gunfire."

Al-Shabab has carried out several attacks in Garissa and across Kenya in the past, including the 2013 attack on an upscale shopping mall in the capital Nairobi.

The group has vowed to punish Kenya for sending troops into Somalia alongside African Union peacekeepers to fight the group.

Speaking to Al Jazeera, Farah Maalim, a former Kenyan Deputy Parliamentary Speaker, described the attack on the university as "scary".

"The university has no less than a 1,000 students. The damage can be colossal, but no one seems to know at this point," Maalim said.

"You cannot fight these isolated attacks with conventional military tactics, which still seems to be the only response."

"There is a possible intelligence lapse here, and that is no excuse [because] we have state of the art of intelligence gathering and plans can be intercepted."

Maalim said al-Shabab was losing the war it has been waging on Somalia and Kenya.  

"They are on the death bed. They need to be in the limelight; that is why they are going for these soft targets," he said.

Garissa University College (GUC), the only public institution of higher learning in the region, opened its doors in 2011, according to the institution's website.

The institution is situated in Garissa County in the northeastern region of Kenya, about 380km from Nairobi, the capital.
(Al Jazeera)