Story highlights Nigerian president: "A terrorist attack on one person is an attack on all of us"

"We don't know what's going to happen next," a Kano resident says

Authorities lift a curfew imposed in Kano after the attacks

The number of deaths is expected to rise, a military official says

Nigeria's president toured his nation's second largest city Sunday after blasts there killed at least 157 people, and left the police headquarters and other government buildings in charred ruins.

"The message I had for the people of Kano is the same message I have for all Nigerians: A terrorist attack on one person is an attack on all of us," President Goodluck Jonathan said in a post on his official Facebook page after the visit.

Jonathan stopped by several attack sites in the northern city, met with the wounded at a hospital and spoke with victims' families.

Authorities have lifted a daytime curfew imposed in Kano after the bombings, which hit eight government sites Friday.

But an overnight curfew remained between 7 p.m. to 6 a.m., according to residents

Shell-shocked residents wandered the streets, looking for loved ones. Others hid behind barricaded doors, too scared to leave for fear of more attacks.

"That's the scary part, not knowing," said Faruk Mohammed, 27, who lives near one of the bombed police stations. "We don't know what's going to happen next, no one thought this would ever happen here. There's a general sense of despair."

The attacks paired bomb blasts with shootings on various sites including police stations, the passport office, state security headquarters and the immigration office.

JUST WATCHED Have militants found Nigeria's flaw? Replay More Videos ... MUST WATCH Have militants found Nigeria's flaw? 00:10

JUST WATCHED Curfew in Kano after deadly attacks Replay More Videos ... MUST WATCH Curfew in Kano after deadly attacks 02:48

JUST WATCHED Boko Haram's terrorizing of Nigeria Replay More Videos ... MUST WATCH Boko Haram's terrorizing of Nigeria 02:40

During the attack, assailants entered a police station, freed detainees and bombed it, authorities said.

They later canvassed the area in a car led by motorcycles, spraying targets with gunfire.

"I counted at least 25 explosions ...," Mohammed said. "Then it went deathly quiet. Kano is a bustling city ... I've lived here for years and it has never been quiet, even at night. But after the bombings stopped, the only noise you could hear were dogs barking."

The number of deaths is expected to rise because hospitals are not equipped to deal with the influx and severity of the injuries, according to a military official who did not want to be named because he is not authorized to talk to the media.

About 50 people were injured and search-and-rescue operations are ongoing, a Red Cross information officer said.

Islamist group Boko Haram -- whose name means "western education is sacrilege" -- claimed responsibility for the blast in a phone call to the Daily Trust, according to journalists at the newspaper.

The group has been blamed for months of widespread bloodshed, with churches and police stations among the targets.

On Sunday, two churches and a security checkpoint were attacked in the neighboring state of Bauchi, the state police commissioner said in a statement. At least 11 people, including police and army personnel, were killed in the checkpoint attack, the commissioner said. There were no casualties reported from the church attacks.

Police said they suspect Boko Haram was involved in the checkpoint attack.

In December, President Goodluck Jonathan declared a state of emergency in four northern states after a series of Christmas Day attacks on churches blamed on Boko Haram.

The man suspected of masterminding those attacks was briefly captured before escaping police custody while being transferred to another prison.

Depending on the faction, Boko Haram's ambitions range from the stricter enforcement of Islamic Sharia law to the total destruction of the government.

Its grievances remain local, but it has attacked international institutions --- such as the United Nations -- on Nigerian soil.

An August 26 attack -- during which a Boko Haram suicide bomber drove a Jeep laden with explosives into the U.N. headquarters in Abuja -- was one of the deadliest in the world body's history. Twenty-four people were killed, including 12 U.N. staff.

The group was formed in 2002 by Islamic preacher Mohammad Yusuf as an outgrowth of ethnic tensions in the country in the 1990s.

Nigeria's population is split between mostly Muslims living in the north and predominantly Christians in the south. Yusuf advocated the institution of Sharia law throughout the northern states and opposed democracy.

The group operated openly out of northeastern Nigeria and staged small-scale attacks against government targets.

In 2009, Nigerian police forces moved to crack down on Boko Haram. Harsh police tactics led to an armed uprising and the arrest of Yusuf, who later died in police custody.

The death spurred the group to begin its attacks on police stations. Ensuing clashes between group members and the police killed hundreds.

The following year, Boko Haram re-emerged as a more radicalized, insurgent style group, staging assassinations and attacks against not only government targets, but also churches and even a beer garden.

"We're dealing with a movement of inchoate rage," said John Campbell, a U.S. ambassador to Nigeria who left his post in 2007.

"It's highly decentralized, but what it has in common is a strongly Islamic character, and hatred for the secular, political economy of Nigeria, particularly the federal and state governments," he said.