Gunmen stormed into a bar, dragged out eight people and killed them in the parking lot, the first of several shootings in this violent border city Wednesday that left 16 dead, including a man in a wheelchair.
In one incident, a car chase and shootout killed three people in front of an elementary school, creating a panic among students, teachers and parents.
Battles between rival drug gangs have made Ciudad Juarez, across the border from El Paso, Texas, one of the world's deadliest cities. More than 800 people have been killed this year in the city of 1.3 million people.
Armed men burst into the Aristos bar in the middle of the night, said Arturo Sandoval, a spokesman for the Chihuahua state attorney general's office. Eight people were forced out into the parking lot and shot to death.
The victims had not been identified, but Sandoval said at least one appeared to be a teenage boy.
The shootout in front of the Benito Juarez elementary school erupted hours later. Sandoval said a woman and two men were found dead inside a car.
Gunmen in a car chased down another vehicle and opened fire in front of the school around noon, said a teacher who asked not to be quoted by name out of fear for his safety.
The teacher said a pregnant teacher and three students suffered panic attacks and were taken to a hospital. Classes were canceled for the rest of the day, and parents rushed to pick up their children.
Gunmen opened fire on another car elsewhere in the city, killing four young men inside, Sandoval said. Separately, a gang of armed men killed a man sitting in a wheelchair on the sidewalk, he said.
Police had no information on the identities of any of the gunmen.
The army, meanwhile, reported that it freed 16 hostages Tuesday at a house in Sabinas Hidalgo, a town near the northern city of Monterrey. One of the hostages was a 1-year-old child.
Troops acting on an anonymous tip arrived at the house in helicopters, a statement said. Gunmen opened fire and soldiers fired back from the air. Two people were found dead inside the house but it was unclear if they were captors or hostages.
Soldiers also seized two tons of marijuana, nine guns and a grenade launcher. It was unclear why the 16 people were being held hostage.
It was the second time in two days that soldiers freed hostages in the northern state of Nuevo Leon. On Monday, troops killed three suspected kidnappers and freed seven of their captives during a raid on a ranch. Two rotting bodies were found in a truck near the ranch.
Meanwhile, four inmates were killed early Tuesday when an armed gang stormed a prison in the northern town of Altamira, the Tamaulipas state government said in a statement.
It was unclear who killed the two men and two women.
A local police report said the gang attacked as 11 inmates were being transferred to the prison, but authorities did not confirm reports that the raid was an attempt to free prisoners or that a gunfight broke out with security forces.
Gang raids on prisons are common in Tamaulipas, a state bordering Texas where a bloody battle has broken out between the Gulf cartel and its former ally, the Zetas gang of hit men.
In the Pacific coast state of Guerrero on Wednesday, gunmen killed the mayor of the small town of Zapotitlan Tablas while he was in the state capital of Chilpancingo.
Mayor Jose Santiago Agustino gained notoriety in 2009, when he complained that a government hospital built in his region more than a decade earlier had never opened. The region is also plagued by violent crime and drug trafficking.