A citywide scavenger hunt turned sour for 40 high school students when Laredo police caught wind of the caper and arrested them on felony charges of theft and engaging in organized criminal activity.

Police accused the students — most of them seniors at Laredo high schools — of swiping up to five truckloads of loot from across town. The scavenger list included items such as city traffic signs and pinatas, police said.

"We will cooperate fully, review the case and collaborate with officials to determine all the facts," said Marco Alvarado, spokesman for the Laredo school district. "If needed, we will take appropriate action as specified in the student Code of Conduct."

Police arrested the 32 adults and eight juveniles early Saturday morning. The students' names were not released.

Officers first uncovered the escapade when a group of five students was pulled over for speeding. The car contained numerous stolen stop signs, a garden hose and other items, police said.

A short time later, the police department started receiving calls from residents who were angry about commotion caused by cars speeding in their neighborhood and stopping at a vacant lot.

Police determined the lot to be a drop-off point for stolen items. Officers then set up surveillance of the area and arrested the students as they came to drop off stolen items, the department said.

The older students were taken to the Webb County Jail, while the younger students were taken to a juvenile detention center. The police also impounded several of the students' vehicles.

Juan Cruz, an attorney for United Independent School District, said the district would review the criminal charges on Monday and figure out what action to take.

A third-degree felony charge of engaging in organized criminal activity is punishable by up to 10 years in prison and a $10,000 fine. A state jail felony theft charge is punishable by up to two years in prison and a fine of up to $10,000.