A timeline provided by Pennsylvania State Police of the hours leading up to the deadly Amish school shooting in Lancaster County:

3 a.m.: The gunman, Charles Carl Roberts IV, arrives home from work after finishing his milk run, picking up milk from Amish farms.

7:30 a.m.: Roberts and his wife, Marie, begin getting their children ready for school.

8:45 a.m.: Roberts walks his children to the school bus stop.

9 a.m.: Marie Roberts leaves for a prayer group; Charles Roberts was to leave the house for a random drug test, a requirement for his job, but did not do so.

Around 10 a.m.: Charles Roberts enters the West Nickel Mines Amish School.

10:30 a.m. Marie Roberts leaves church with a friend, and drops off the friend before returning home.

Around 10:30 a.m.: The Amish teacher and another adult at the school run to a nearby farmhouse, and someone calls 911 to report a hostage situation.

10:45 a.m.-10:50 a.m.: Marie Roberts tries to call her husband from the couple's home phone; Charles Roberts had taken her cell phone with him. The first police units arrive.

10:50 a.m.: Roberts talks to his wife but will not disclose where he is, and tells her, "I am not coming home. The police are here." He then tells her he molested two young family members 20 years earlier and tells her where to find suicide notes he has left in the house.

Just after 11 a.m.: Charles Roberts tells a dispatcher he will open fire on the children if police don't back away from the building. Within seconds, troopers hear gunfire inside.

Source: Pennsylvania State Police Commissioner Jeffrey B. Miller.