A D.C. elementary school student was charged with possession of a controlled substance Thursday after being accused of taking cocaine to school and sharing it with four classmates who were hospitalized after ingesting the drug.

Police and school officials said that the four students at Thomson Elementary, at 1200 L St. NW, were never seriously ill and that their examinations at Children’s National Medical Center were precautionary. A fifth student, who did not consume the drug, was taken to the hospital as a precaution.

The incident stunned parents who received word at afternoon pickup and jolted officials accustomed to dealing with an urban school system’s usual array of crime and other emergencies. No one could remember a drug incident involving students so young.

“This is very unusual,” said Safiya Simmons, a D.C. schools spokeswoman. “Not something we’re accustomed to dealing with.”

Officials did not disclose the children’s grade levels and said they were trying to determine how the student acquired the undisclosed amount of cocaine. Some of the students ingested it orally and others inhaled it, authorities said, but they did not know how much each student consumed. Thomson serves students in pre-kindergarten through fifth grade.

When the students became ill, a teacher spoke with the student suspected of distributing a substance and alerted the main office. The students were evaluated by a school nurse and EMTs before being taken to the hospital. School officials said police later determined that the substance was cocaine.

Drug use among elementary school students is not widespread, and the federal government’s two largest annual reports don’t survey anyone younger than 12. Among youths surveyed, cocaine use is relatively rare. Overall, however, teen drug use has recently begun to increase after decades of decline. Drugs most abused by 12th-graders are marijuana and prescription and over-the-counter medications, according to the National Institute of Drug Abuse.

“It is unusual to have elementary school students using cocaine. However, it’s not that unusual for young students to try substances,” said Susan E. Foster of the National Center on Addiction and Substance Abuse at Columbia University.

On average, youths who abuse tobacco, alcohol or marijuana tried it for the first time when they were about 13, she said, and the earlier their initiation, the more likely they were to become addicted. “Usually, their sources are their friends or their own homes,” Foster said.

Principal Albert DuPont put out an automated phone call to parents about 2 p.m. disclosing the incident. Officials also prepared a letter for parents — in English, Spanish and Chinese, to reflect the population of the school, which is near the Washington Convention Center.

Parents expressed shock and incredulity.

“I think it’s terrible. I’ve never heard of anything like this before,” said Terrance Boseman, whose son Kahlil attends kindergarten. “It’s a great school, but you just think that this is an unbelievable situation.”

“Incredible,” said Ling Ren, who has a 3-year-old in Head Start and a 5-year-old in kindergarten.

School will not be in session Friday because it is a professional development day for D.C. teachers. But officials said counselors will be at the school Monday to discuss the incident with students and teachers.

In his letter to parents, DuPont said that the incident was unusual but that it would be treated “very seriously.” He also asked parents to tell their children never to accept food or other substances from another child, and he stressed the importance of telling an adult when they see or hear something about drugs.

“Assure your child that the adults are making sure they are safe,” DuPont wrote.

Staff writers Jenna Johnson and Paul Duggan contributed to this report.