Three people have been shot dead after a gunman walked into a New Jersey Pathmark store and killed two staff members including an 18-year-old girl.

The shooter was an employee of Pathmark and entered the Old Bridge store around 4:00 a.m. with a shotgun and opened fire on staff who were stacking shelves before the scheduled 6:00 a.m. opening.

When police arrived at the store which is 25-miles from New York City they moved the employees to a nearby T.G.I. Friday’s where they were checked out by emergency workers.

Three people have been shot dead after a gunman walked into a New Jersey Pathmark store and killed two staff members including an 18-year-old girl

“This is the worst phone call a mayor can receive,” said the mayor of Old Bridge Owen Henry.

“You can prepare for these things but you can’t prevent them.”

It is unknown how many other people were in the store before the police arrived but several members of staff would have been inside as the Pathmark was preparing to open at 6:00 a.m.

Police said that they received a telephone call around 4:30 a.m. informing them that shots were being fired from inside the supermarket.

According to store employees who fled the scene, the gunman entered into the Pathmark wielding a shotgun and began shooting.

It is not known how the shooter entered the building before opening hours.

The local police have sealed off the area and the case was turned over to the Middlesex County Prosecutor’s Office.

Witnesses inside said that there were around a dozen staff stacking shelves before opening.

The incident comes just weeks after a series of mass shootings shook the country.

In July, a gunman opened fire in a crowded Colorado movie theater and earlier this month a white supremacist opened fire in a Sikh temple in Wisconsin.

And last week a disgruntled former employee shot his former boss on the streets of New York City before becoming involved in shoot-out with police that left nine bystanders injured.

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