Mexico police killed as wave of violence continues
At least nine Mexican police officers have been shot and killed in an ambush on their convoy in western Jalisco state - the sixth multiple killing in Mexico in less than a week.
Earlier, five women in Ciudad Juarez were killed when buses taking them home from work were ambushed by gunmen.
In Mexico City, six youths were shot dead in what police say may have been a gang-related feud.
Mexico is suffering a wave of violence, mostly linked to the drugs trade.
The 20 officers in the convoy in Jalisco were on patrol when they were attacked by gunmen in at least 10 sport utility vehicles, said a police statement.
Nine officers were killed, while a 10th is still missing.
Separately, at least five people were injured in grenade attacks in a suburb of Guadalajara, the state capital of Jalisco.
Two of those wounded were toddlers, reported the Associated Press news agency, and a third was a 17-year-old girl.
The killings in Mexico City may have been drug-related, said Miguel Angel Mancera of the attorney-general's office, but there had also been disputes between local car-jacking gangs.
The Tepito district, just north of Mexico City's historic centre, is a poor neighbourhood with a high crime rate.
The young men were standing outside a shop in the middle of the night when gunmen approached and opened fire before escaping in a car.
However, mass shootings are rare in the capital.
"We would like to reassure the population that we are going to find those responsible," Mr Mancera said.
The killings have raised concerns that the drug-related violence raging in the northern border states and some other regions of Mexico is coming to the capital.
"Massacres have arrived in the federal district," declared the newspaper El Universal.
The latest killings in Ciudad Juarez, a border city at the heart of the drugs conflict, do not appear to be drug-related.
Gunmen opened fire indiscriminately on three buses carrying female factory workers back from a shift at a plant making car parts.
At least 14 others were wounded in the attack, with some in a critical condition.
Some 28,000 people have died in drugs-related violence in Mexico since 2006.
More than 7,000 people have died in the violence in 2010 - making it the bloodiest year since President Felipe Calderon dispatched some 50,000 troops to take on the drug cartels over the past four years.