Four teen-agers have been arrested in Natchitoches on charges they were plotting to kill one of their mothers.

The group came under investigation after a 15-year-old boy and a 13-year-old girl were involved in a wreck in Natchitoches Parish last week. The girl was driving a car taken from her mother in Natchitoches, police said.

The mother did not press charges and the two children were released to their parents.

Four days later, Natchitoches police said, the mother contacted them and said she had been looking around her daughter's room and found a stack of handwritten notes that indicated her daughter and some friends were planning to kill the mother.

Natchitoches police Lt. Brad Walker said the teens had been planning it for at least a month. Police did not disclose an alleged motive.

"They planned to kill the mother, steal her vehicle and take off to another state," Walker said. "What they were going to do once they got there, who knows. It was several notes; detailed plans. More than one plan: Plan A, Plan C, Plan D; if something didn't work, this is what we're going to do. It was pretty detailed."

After an investigation, police concluded four juveniles -- two 15-year-old boys and two 13-year-old girls -- took part in the planning. They were charged with conspiracy to commit murder and placed in a juvenile detention center.

Their names were not made public because they are juveniles.

"I think the only reason this plan didn't go through (is) family members of the mother came in during the night unexpectedly -- the night this was supposed to happen," Walker said. "They abandoned those plans and went with stealing the vehicle."

Authorities said the teens also wrote about plans to kidnap another juvenile who had broken up with one of the girls.