A Charles County woman was one angry mom this week -- enraged enough to try to block her daughter's school bus, spit at the driver, pull an ice pick from her purse, and then hop on the bus's hood, police said.

The apparent reason: A driver attempted to move her daughter to a different bus seat because of the girl's alleged rowdy behavior.

According to the school district, the trouble began at Westlake High School on Wednesday afternoon, when the bus driver tried to move the student. When the girl refused, a school administrator took her to the office to call her mother for a ride home.

The next morning, the girl's mother, Arlene Watson Phillips, confronted the driver at a bus stop in the 2700 block of Hale Court in Waldorf, police said. She unfolded a lawn chair and sat in front of the bus, according to school system spokeswoman Katie O'Malley-Simpson.

According to a report filed in District Court by the Charles County Sheriff's Office, the incident occurred as follows: Phillips boarded the bus and began cursing and spitting at the driver, Lynnell Adams, in front of at least 20 students.

Adams ushered Phillips off the bus and closed the doors. Phillips then tried to pry the doors open, pulling the doors off their tracks.

Outside the bus, Phillips pulled out an ice pick with a blue handle from her purse. Adams tried to drive away, but Phillips climbed onto the hood of the bus. From inside the bus, Adams used a radio to call school officials, who called police.

Phillips did not return calls for comment yesterday.

Sheriff's deputies arrested Phillips and charged her with second-degree assault, malicious destruction of property, carrying a concealed and deadly weapon, disorderly conduct, disturbing the peace and false imprisonment.

She is scheduled for a preliminary hearing June 13 in Charles County District Court.

Because of the ongoing investigation, Adams declined to comment yesterday and referred questions to her sister Vernell Jones.

"It was scary,'' said Jones, who is president of the Southern Maryland Association for the Education of Young Children. "I know she was worried about the safety of the kids."

After being interviewed by the sheriff's officers, Adams delivered the students to school. They were a little late but not harmed, according to the school system.

Phillips's daughter did not ride the bus to school after the incident.

Terri Henson, president of the high school's Parent Teacher Student Organization, said she was "quite stunned'' when she learned of the incident. She commended Adams for protecting the students and said, "The kids seem to be fine."

In a letter to parents Thursday, Principal L.C. Martin said that some students "expressed concerns about the parent's actions" and that the school planned to provide extra staff at the bus stop yesterday to prevent further disruptions.

Martin also asked parents to contact the school -- not individual bus drivers -- when they have problems.

O'Malley-Simpson said Phillips had called the school system's transportation office to complain about the seat assignment late Wednesday.

"He was going to look into it on Thursday morning," O'Malley-Simpson said.

Arlene Watson Phillips is charged with, among other things, assault and carrying a concealed weapon.