Updated at 7:25 p.m.

WESTFIELD, NJ –  An additional charge of third-degree possession of a firearm in or upon the grounds of an educational institution has been filed against the man who came to an elementary school in Westfield last Thursday afternoon armed with a handgun and hollow point bullets, the Union County Prosecutor's office said Monday.

MORE: Westfield Police Chief Shares Praise for Department After Tragedy Averted

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As reported last week, a tip from police in Delaware helped authorities to arrest Thomas J. Wilkie, 46, of Bear, Delaware, acting Union County Prosecutor Jennifer Davenport said Friday.

Wilkie was arrested outside of Tamaques Elementary School after classes had let out for the day, Davenport said in a statement.

Wilkie is also charged with second-degree unlawful possession of a weapon, fourth-degree possession of hollow-point bullets and fourth-degree trespassing on school grounds, Davenport said.

At 3:55 p.m. on Thursday, Westfield police responded to Tamaques Elementary School on a report from the New Castle County Police Department in Delaware that a man, later identified as Wilkie, was en route to the school and may be armed, the prosecutor’s statement said.

The school was placed on lockdown as a precautionary measure and to identify any other potential threats, Davenport said.

Officers located Wilkie in the front seat of his vehicle, a 2019 Mitsubishi SUV, parked in the school’s parking lot, holding a .45-caliber handgun loaded with hollow-point bullets, she said. Two additional loaded clips of ammunition were recovered from Wilkie’s person, while 130 additional rounds of ammunition were located in the vehicle’s trunk, Davenport stated.

Motive and the defendant’s movements leading up to the arrest both remain under investigation, Mark Spivey, a spokesman for the prosecutor's office, said Friday.

A witness had told TAPinto Westfield that about eight officers surrounded the man later identified as Wilkie and forced him to lie on the ground for the arrest. The school building was placed on lockdown during the incident, Westfield police had said.

“A security sweep of the building and its perimeter was conducted prior to the lockdown being lifted at approximately 5:32 p.m. and children were released to their parents without incident,” Westfield Police Chief Chris Battiloro had said Thursday evening. “Police canines were brought in for a final, precautionary sweep.”

Wilkie was lodged in Union County Jail pending a first appearance and detention hearing scheduled to take place the morning of Wednesday, June 19, Davenport said.

Convictions on second-degree criminal charges are commonly punishable by 5 to 10 years in state prison, authorities said.

Westfield Police Chief Chris Battiloro commended responding Officers Jeffrey Johnson and Michael Pollock and all of the officers, detectives and supervisors who responded to the incident Monday in a memo shared with TAPinto Westfield.

“I am certain that your brave and courageous actions thwarted any chance of tragedy and ensured the safety and well-being of all those children,” he wrote in part. “I am extremely proud of each and every one of you.”

Westfield Mayor Shelley Brindle had praise for the authorities.

“I’m very grateful for the swift work of our Town of Westfield, NJ Police Department in apprehending an armed suspect in the parking lot of Tamaques Elementary School, a situation which is every parent’s worst nightmare," Brindle said on Facebook last week. "Thank you to our WPD, the Tamaques administration, and to the Board of Education for working together to ensure all our students and faculty were safe.”