By Dave Savini

(CBS) — Every three weeks: That is how often mass shootings occur, according to federal officials. Places of worship have fallen victim.

CBS 2’s Dave Savini talks with religious leaders and law enforcement representatives about what they are doing to protect congregants.

Their efforts include some very serious training, such as simulated “active shooter” drills.

The threat of this happening is all too real for many houses of worship.

“Somebody could come and start shooting. That is a present danger that we are quite concerned with,” says Oussama Jammal, vice president of the Mosque Foundation.

“We want to make sure we’re prepared,” agrees Rabbi Avraham Kagan of Chabad of Illinois.

Attacks on religious places have already occurred in the Chicago region. In 2012, six people were shot to death at a Wisconsin Sikh temple.

In Cook County alone, there are approximately 5,206 houses of worship involving all religions.  They are considered possible targets because they are open for anyone to enter to pray, but unfortunately, those who enter could also cause harm.

Orland Park Police Chief Tim McCarthy says a mosque in his community was targeted. Somebody fired a bullet at the mosque’s dome.

His is the first local police department to acquire FAA certification to use a drone, which could be used for “getting eyes” overhead a shooting scene. McCarthy’s department is also collecting digital maps of houses of worships, so that officers can be familiar with interior layouts.

Ten thousand first-responders were trained last year under a program for officers and paramedics, says Enest Brown, head of Cook County Homeland Security.

Also, they’ve trained religious leaders through the Interfaith Security Advisory Council. The idea is to have religious leaders identify signs that violence may erupt.

When confronted by a shooter, Chief McCarthy says, congregants should run, hide or fight.