By Claire Marshall
BBC News, Nuevo Laredo
One female police officer has been killed and another badly hurt in a drive-by shooting in the northern Mexican town of Nuevo Laredo.
The killing takes the number of police murdered in the town this year to 15, with about 110 killed during 2005.
The assassination took place close to the border with the US state of Texas.
Violence in Nuevo Laredo is the result of a vicious turf war being fought between two powerful drug cartels for control of the lucrative drug trade.
This brazen assassination, in the middle of the afternoon, took place in central Nuevo Laredo, just six blocks from the international bridge which crosses into Texas.
It came just two days after the US reopened its consulate, which had been shut after a shootout between drug gangs in which bazookas and machine guns were used.
Witnesses at the scene said the two female police officers were in a car driving home after their shift.
They were wearing civilian clothes when they were passed by a car driven by a young man.
Another man in the car was holding a weapon.
Police are struggling to control violence across Nuevo Laredo
The gunman opened fire, instantly killing one of the women.
The other police officer, who was driving, was also shot and seriously injured.
Of the 15 police officers murdered so far this year in Nuevo Laredo, this was the first woman.
She is thought to have been a police radio operator.
The latest shootings come at the height of an operation called Secure Mexico.
Launched by President Vicente Fox after the murder of the city's police chief, the aim of the operation is to restore calm to Nuevo Laredo.
Hundreds of troops and federal police are operating in and around the city.
New recruits to the local police have been given special uniforms and equipment.
However, as has been the case in the past with these assassinations, the authorities all arrived too late to be able to arrest any suspects.