Winslow Township High School was locked down and students were confined to their classrooms yesterday while authorities investigated reports that a gunman was inside.

The incident lasted for several hours during a search of the Camden County school, said Bill Shralow, a spokesman for the county Prosecutor's Office.

No weapon or suspect was located, but the investigation will continue. "It hasn't been disproved," Shralow said. "They're obviously not going to drop the whole matter."

No threats were made, he added.

The school, which has nearly 1,700 students in grades nine through 12, was the target of a foiled gun-and-terror plot last year. The district has been plagued recently with violence and threats that have interrupted classes.

Yesterday's lockdown began around 12:30 p.m., when a Winslow Township police officer assigned to the school as a resource officer received a report of a man with a gun in his waistband inside the school, Shralow said.

Students were kept in their classrooms during the search. Some parents, who received text messages from their children, rushed to the school. Students were sent home beginning around 4 p.m., after their normal dismissal time.

Superintendent Daniel Swirsky did not return messages left at his office.

Last year, authorities thwarted a plot by four Winslow High students who compiled a hit list of about 25 people and planned to gun down students, teachers and others.

The youths hatched a plan to purchase weapons and allegedly planned to start a food fight in the cafeteria. Authorities said they planned to use that incident to start throwing chairs and executing people at will.

Three of the teenagers involved in the plot were sentenced to state prison or juvenile detention, while a fourth, who was said to have minimal involvement in the plan, received probation.

This year, Winslow Middle, which is adjacent to the high school, has also had several disruptive incidents.

In February, an eighth grader was charged with writing notes that threatened at least two female classmates, and a 13-year-old brought an unloaded gun to school. And last month, a 15-year-old was charged with false public alarms and false terroristic threats after a note was found containing a bomb threat.

Winslow residents rejected a proposal last month to raise an extra $700,000 through property taxes to buy security equipment and hire more security.

With more than 6,200 students, Winslow is the fourth-largest district in Camden County, serving the sprawling 58-square mile municipality.

Contact staff writer Melanie Burney at 856-779-3876 or mburney@phillynews.com.