Mexico has seen several killings of police officials in recent days
Three top Mexican police officials have been shot dead in as many days while the country's fight against drug-trafficking continues.
Assailants sprayed the car of the deputy police chief of the border city of Ciudad Juarez on Saturday, killing Juan Antonio Roman Garcia.
The head of Mexico City's anti-kidnap unit was killed on Friday.
On Thursday, the director of national police operations against drug traffickers was shot dead.
Speaking before the latest killing, Mexican President Felipe Calderon said such attacks would not deter his efforts to continue his government's campaign against drug-trafficking cartels.
"We have to come together to confront this evil, we Mexicans have to definitively and categorically say 'That's enough!'," he said at a police memorial service.
"We can't accept this situation. We have to take back our streets."
'City in mourning'
Mr Garcia was shot dead outside his home in Ciudad Juarez, which borders Texas.
President Calderon was at a memorial to dead police officers this week
His name had appeared at the top of a "hit list" left at a monument for fallen police officers a few months earlier.
"His death has plunged the city into mourning because he was an exemplary officer with an impeccable 20-year record who fulfilled his duties until his last breath, despite the dangers," said the city's mayor, Jose Reyes Ferriz.
All police officers have been ordered to take added precautions, he added.
Mexico City anti-kidnap chief Esteban Robles died after being shot several times outside his home on Friday.
The previous day, the director of national police operations against drug traffickers, Edgar Millan Gomez, was shot dead outside his home in the capital.
Earlier in the week, another senior policeman in Ciudad Juarez, Saul Pena, was gunned down as he left police headquarters.
Mexico has seen a surge in drug-related killings recently.
Last year, 2,500 people were killed while so far this year, about 1,100 people have been killed.
President Calderon has sent nearly 30,000 soldiers and federal police to fight Mexico's powerful drug cartels since he took office in 2006.
The drugs cartels have fought back by attacking security forces.
They are also fighting each other to control lucrative trafficking routes.
The White House has again called on the US Congress to pass legislation that would allow more than $1bn of aid to be used in the fight against Mexico's drug cartels.