MAIDUGURI, Nigeria (AP) — Sabotaged phone lines prevented students from warning friends and possibly saving their lives in the attack in which 22 college students were killed earlier this week, survivors said Friday.

Assailants attacked student accommodation in the northeastern town of Mubi late Monday, shooting some and stabbing others to death, near Federal Polytechnic Mubi, a college in the northeastern town of Mubi. Police say they killed at least 22 students and three others.

John Bello, a Mubi college student, said Friday that only one mobile phone network was working in the town and that it was congested.

"We could maybe have alerted some of those that were killed if the networks weren't down," Bello said.

"Many students didn't find out what happened until they saw students running (away)," said Danjuma Aiso, another student. "When we tried to call those in the affected area, our calls didn't go through," he added.

Aiso said he heard gunshots for about five hours from his hiding place. However, Adamawa state police spokesman Ibrahim Mohammed said the attacks ended much more quickly although he could not say Friday how long authorities believe they lasted. He said police are still investigating and that there had been no arrests. No group has claimed responsibility for the attacks.

Days after the killings hit the secluded college, many questions remain about what actually happened. Sabotaged phone lines are partly to blame for the information vacuum as people in the town struggle to communicate with those in other parts of Nigeria.

The killings came a month after the radical Islamist sect known as Boko Haram attacked more than 20 phone masts in Nigeria's north that effectively crippled communications in some areas.

In Nigeria, home to more than 160 million people, mobile phones are the main method of communication in both cities and rural communities. Landlines remain almost nonexistent, as the state-run telephone company has collapsed and repeated efforts to privatize it have failed. More 87 million mobile phone lines were in use in 2009, according to estimates.

Days after the attack, the difficult communications are still having a negative effect.

Police has not yet notified next-of-kin, Mohammed said Friday, leaving parents like Dauda Mbaya dreading that their children may be among the dead.

"Someone told me (my daughter) is OK, but I have not heard from her yet," Mbaya, a journalist based in Maiduguri, a city some 100 miles (170 kilometers) away, said Friday.

The Mubi killings show how the communication breakdown is making people even more anxious and vulnerable to widespread crime.

"The lack of good (phone networks) makes life very tough and insecure for us," said Abba Ado, a security guard at a bank in the Maiduguri, "Each time we hear bomb blasts or gun shots, we become agitated, because we cannot get across to our wives at home or our children at school."

Yuguda Ibrahim, a cameraman, said his neighbor's pregnant wife could not call her husband as she started to feel labor pains.

"She almost died because all the calls she tried to place across to her husband wouldn't get through," said Ibrahim. "The child was already coming out when my wife heard her groaning and helped her deliver in their bedroom."