Students and teachers are returning to school this morning for the first time since the school shooting tragedy in Newtown, Conn., last Friday, and at least one local school district is stepping up security.

Hillsborough County Schools will have an increased law enforcement presence provided by both the sheriff's office and Tampa Police department, authorities said.

All of the schools in the district were placed on modified lockdown Monday morning, shortly after officials reported finding a bullet on a school bus. Officials said the students who were on that bus will be questioned and their bags and lockers searched.

At elementary schools, officers from traffic marine patrol and special incident management who typically handle large scale events will be assigned to elementary schools. Additionally, the Tampa police helicopter will fly over schools and extra officers will patrol middle and high schools all week.

"I know that after the weekend, everybody has been inundated with all these disturbing images of what happened in Connecticut, so we just want to demonstrate to parents and to students that school is a safe and secure place," said Hillsborough County Schools communications officers Steve Hegarty.

In Newtown Conn., last Friday, a lone gunman broke into Sandy Hook Elementary School and killed 26 people, including 20 young children, before committing suicide. The story has gripped the nation for days.

On the administrative side, Tampa police will conduct site surveys as needed at city schools this week to determine whether there are ways to improve security. The surveys also serve to make teachers and staff know how to respond to an emergency on campus.

Pinellas County Schools did not announce any plans to add extra law enforcement officers this week. And officials at Pasco County Schools said they couldn't disclose any changes to their security plans.

In Hernando County, sheriff's office officials said they have been "fine turning" their school security operations. An active operations plan includes the use of marked and unmarked patrol vehicles, along with "other assets of the sheriff's office," a news release said.