(CNN) Pennsylvania state Sen. Michael Folmer handed in his letter of resignation Wednesday amid allegations that police found child pornography on his phone, Senate leaders said.

"We are sickened and disturbed by the charges brought against Mike Folmer yesterday. We have reviewed the criminal complaint and spoke with Mike Folmer early this morning to insist on his resignation from the Senate," read a statement from Senate President Pro Tempore Joe Scarnati and Senate Majority Leader Jake Corman.

On Tuesday, Scarnati and Corman said they would immediately remove Folmer as chair of the state government committee.

Folmer's seat is now vacant. According to the state constitution, the Senate president must issue a writ for a special election to fill the seat.

CNN could not immediately reach Folmer for comment.

A preliminary hearing in his case is scheduled for September 26, according to the office of state Attorney General Josh Shapiro.

Investigators found child pornography on Folmer's phone while executing a search warrant at his Lebanon home, Shapiro's office said in a news release.

The probe was launched after a tip reported that Tumblr had discovered a user who uploaded an image of child pornography using the application. Further investigation led to Folmer's home, the statement said.

"This defendant serves as a state Senator and was entrusted to honor and represent his community in the Pennsylvania Capitol," Shapiro said in a statement.

Folmer was charged Tuesday with sexual abuse of children, possession of child pornography and criminal use of a communication facility.

"I will continue to say it -- no one is above the law, no matter what position of power they hold," Shapiro said. "I will continue to work to protect children and hold those who abuse them accountable."

Pennsylvania Gov. Tom Wolf called the Republican lawmaker's decision to step down "the right decision," spokesman J.J. Abbott said.

"We elect leaders to serve as a voice for those who do not have the ability to advocate for their own needs, demanding that they will protect our children, families, and communities," Wolf said in a statement released earlier Wednesday. "The charges against Senator Folmer are disgusting and beyond comprehension, and show he has taken advantage of the trust and privilege afforded by the people of Pennsylvania."