Members of the Mexican Army secure an area outside the prison of Ciudad Juarez. AFP

Seven people were killed Monday in northern Mexico's Ciudad Juarez during a police operation to recapture prisoners who escaped after an attack at their facility, state authorities announced.

Gunmen attacked the border city's state prison on Sunday at dawn, leaving nearly 20 people dead and allowing the prisoners, which include a gang leader, to flee.

Monday's deaths — two agents from the state prosecutor's office and five alleged criminals -- took the total fatalities related to the attack to 26, according to a statement from the Chihuahua Public Security Department.

Defense Minister Luis Cresencio Sandoval had earlier told reporters that ten guards, seven prisoners and two attackers had died in Sunday's assault on the prison, which has been attributed to drug traffickers.

Fourteen inmates and a guard were injured and five attackers were captured, Sandoval said.

The 25 escapees included Ernesto Alfredo Pinon, known as "El Neto," the leader of a gang allied with the Juarez drug cartel, Security Minister Rosa Icela Rodriguez said.

Pinon was sentenced to more than 200 years in prison in 2010 for kidnapping and murder, according to the Chihuahua state prosecutor's office.

The attackers, traveling in armored vehicles, launched the assault when relatives of the inmates were lined up for New Year's visits.

Ciudad Juarez, which sits across the border from El Paso, Texas, has seen years of violent clashes between security forces and rival drug cartels.

The prison itself has seen multiple breakouts of fighting and riots, notably in March 2009 when 20 people died.

Mexican detention centers suffer from chronic overcrowding and violence, which has worsened in recent years due to conflict between criminal groups.

Agence France-Presse