RAMADI, Iraq - Militants took hundreds of students and staff hostage at a university in the Iraqi city of Ramadi on Saturday, sparking an assault led by special forces in which they were freed, officials said. And in northern Iraq, heavy fighting between security forces and militants entered its second day, killing 59 people.

Iraq is suffering its worst violence in years, and militants have launched major operations in multiple provinces in recent days that have killed well over 100 people and highlighted their long reach.

In Ramadi, Islamic State of Iraq and the Levant gunmen infiltrated Anbar University from the nearby Al-Tasha area, killed its guards and then blew up a bridge leading to its main gate, police said. An AFP journalist said special forces spearheaded an assault to retake the campus, with heavy gunfire heard.

Security forces “liberated all of the male and female student hostages from the dormitories in Anbar University” and regained control of checkpoints at its entrances, Deputy Interior Minister Adnan al-Assadi said in an emailed statement. And interior ministry spokesman Brigadier General Saad Maan told AFP that all of the hostages had been freed, without giving any casualty figures. The AFP journalist saw security forces bring in buses to take weeping hostages away from one of the women’s dorms, but said that fighting at the university was still ongoing. Police officers put the number of hostages at the start of the incident at 2,500, though that figure could not be independently confirmed.

A wave of car bombs exploded in different districts across the Iraqi capital late on Saturday, killing more than 60 people, security and medical sources said. There were a dozen blasts in total, the deadliest of which occurred in the Bayaa neighborhood, where a car bomb killed 23 people, many of them young people playing billiards. No group immediately claimed responsibility for any of the attacks, but the Shi’ite community is a target for Sunni Islamist insurgents who have been regaining ground and momentum in Iraq over the past year.

In the past three days, militants have overrun parts of two cities. On Saturday, they occupied a university in the western province of Anbar, taking hundreds of students and staff hostage. Last year was Iraq’s bloodiest since violence began to ease from its climax in 2006-07. Nearly 800 people were killed in May alone, according to the United Nations, the highest monthly death toll this year so far.

Before the assault, a student told AFP by telephone from inside the university that she and other women were ordered to gather in one place, after which the leader of the militants addressed them. “We will teach you a lesson you will never forget,” he said, according to the student’s account. In the northern city of Mosul, heavy fighting between militants and security forces entered its second day on Saturday, killing 21 police and 38 militants, an officer and mortuary employee said.

Fighting erupted in Mosul on Friday morning and continued into the night, while twin suicide bombings targeted a minority group east of the city, and soldiers shot dead suicide bombers to its south.

At least 36 people were killed in Friday’s violence in Mosul and elsewhere in Nineveh province.

A day earlier, militants seized several parts of Samarra in a major assault that was only repelled after house-to-house fighting and helicopter strikes in which dozens died.

A crisis broke out in the desert province of Anbar, west of Baghdad, in December when security forces dismantled a longstanding Sunni Arab protest camp near provincial capital Ramadi.

Anti-government fighters subsequently seized control of parts of Ramadi and all of Fallujah, to its east, and security forces have so far failed to drive them out.

The United Nations said on Friday that the conflict in Anbar is believed to have forced nearly 480,000 people from their homes. They join some 1.1 million others displaced by past years of violence in Iraq.

The Anbar crisis also kept some residents of the province, especially those in Fallujah, from being able to vote in April 30 parliamentary polls.

More than 900 people were killed last month, according to figures separately compiled by the United Nations and the government. So far this year, more than 4,300 people have been killed, according to AFP figures.

Officials blame external factors for the rising bloodshed, particularly the civil war in neighbouring Syria. But analysts say widespread Sunni Arab anger with the government has also been a major factor.