As reported by James McKinley Jr. in the New York Times:
On the night of May 17, dozens of men with assault rifles rolled into town in several trucks and shot up the place [Villa Ahumada]. They killed the police chief, two officers and three civilians. Then they carried off about 10 people, witnesses said. Only one has been found, dead and wrapped in a carpet in Ciudad Juárez.
The entire municipal police force quit after the attack, and officials fled the town for several days, leaving so hastily that they did not release the petty criminals held in the town lockup. The state and federal governments sent in 300 troops and 16 state police officers, restoring an uneasy semblance of order. But townspeople remain terrified.