SALEM - A machete-shoplifting woman swallowed a handful of Xanax and threatened to zap officers with a stun gun before finally being arrested Wednesday afternoon in a Walmart parking lot, police said.

Sara Rivera, 28, of Haverhill, Mass., is charged with willful concealment.

The incident happened about 1:30 p.m. when a store loss-prevention employee tried to stop Rivera in the parking lot. Police were called for a "combative female shoplifter" who had swallowed a handful of unknown pills, according to a police news release.

When officers and firefighters arrived on the scene, Rivera allegedly was standing in the parking lot, her arms outstretched and incessantly blowing an air horn.

She refused to cooperate, police said, and was arrested after a brief struggle during which she threatened to use a Taser on the officers. A stun gun was found tucked into her waistband, according to police.

Rivera is accused of stealing about $1,000 in items from Walmart including horror movies, a machete and perfumes.

Police said she swallowed between 10 and 15 Xanax, medication used to treat anxiety and panic attacks, and was treated on the scene by fire personnel before being taken to the police station for processing.

Once she was booked, Rivera was transported to Parkland Medical Center to be medically cleared for incarceration, according to the news release.

She was transported to Rockingham County jail pending arraignment in 10th Circuit Court, Salem District Division.