By Nick Miles
BBC Central America correspondent
The decapitated heads of two young women have been thrown from a road near a police station in the El Salvadorean capital.
The victims were probably between 15 and 20 years old, police say.
It appears they were decapitated just before arriving at
the spot, because they [the heads] were still losing
The murders are the latest in a series of gruesome killings that have taken place in El Salvador and neighbouring Guatemala in recent months.
El Salvador has one of the highest murder rates in Latin America but the recent spate of killings of young women has been particularly shocking.
The heads of the two latest victims were found just a few metres away from a police station on the outskirts of the capital, San Salvador.
Francisco Parada, the assistant commissioner of the national police, said investigations were under way to track down the bodies of the two women.
There have been at least half a dozen cases since November in which mostly female body parts have been found across the country.
The situation is even worse in neighbouring Guatemala, where 150 women were killed in the first three months of this year - twice as many as a year ago. Many had been dismembered.
On Thursday a Guatemalan pressure group, the Network Against Violence Against Women, called on the authorities to do more to bring an end to the killings.
Several suspects - all reported to be gang members - have been taken into custody but there have been no convictions.
Both El Salvador and Guatemala are plagued by thousands of street gangs whose initiation rites often involve taking part in random murders.