A local government official said hundreds were also injured when the attackers bombed a city police headquarters, three other police stations and six churches in Damaturu late Friday.
"Sixty-three people (are) confirmed dead," the official who asked not to be named said.
A lawyer who visited Damaturu's government hospital Saturday looking for a missing friend said he counted 60 bodies in the morgue, "all brought in yesterday from the attacks."
The lawyer, who asked not to be named, told AFP he found the friend, a policeman, among the corpses.
He said anxious relatives were flocking to the hospital in search of loved ones.
No group has claimed responsibility for the attacks.
A senior local government official in the city, who did not want to be identified because he did not have permission to speak to the media, told AFP that the hospital was full to the brim with wounded.
"The general hospital is full with people who were injured in the attack. If I say there are hundreds injured, it's not an over-estimation. Everywhere is full with the injured," he said, without giving a death toll.
The attackers bombed their targets then took on the security forces in gun battles.
A mason working at the police headquarters in Damaturu at the time of the attack said he saw the bodies of five policemen as he made good his escape after the bomb went off.
"I was plastering a building in the police headquarters when I heard a loud blast. I was thrown to the ground, and the window I had just fixed was blown up from the impact of the blast. I believe I saw five dead men. ... They were men in police uniform," Adamu Mohammed said.
He said he saw several others injured as he scaled a fence to flee the scene.
In a mainly Christian neighbourhood of Damaturu called Jerusalem, six churches were bombed in addition to a police station.
"A police station and a mechanical workshop of the police were attacked. Six churches in the area were also bombed," said resident Edwin Silas, adding: "The whole city is traumatised."
Soldiers and police have mounted checkpoints in parts of the city, searching vehicles and carrying out pat-downs of drivers and passengers.
In the outlying town of Potiskum, a grenade narrowly missed a police station and an ensuing gun battle left at least one policeman dead. The Red Cross official said two had died there.
