Authorities, led by the Colorado Bureau of Investigation, continue to investigate the murder of a 16-year-old girl, and the man they say shot her before killing himself.

Early examination of the facts leave few answers, just a common feeling among law enforcement officers.

"Because of the senseless actions of a lone gunman, we are grieving tonight," said Park County Sheriff Fred Wegener at a news conference Wednesday night.

The unthinkable happened in their backyard, in the halls of Platte Canyon High, where a man with a gun took hostages and started a four hour standoff that concluded tragically in a hail of bullets.

"Officers breached the classroom with explosives," Wegener explained. "Within seconds the suspect shot at SWAT officers, then shot one of the two female hostages, then shot himself," he said.

The victim is 16-year-old Emily Keyes. A Flight-For-Life helicopter carried her to St. Anthony's Hospital in Denver, but doctors could not save her life.

"Our hearts, our prayers are with students, staff and families. Especially the family of the student we lost," said superintendent Jim Walpole.

Now investigators are turning their attention to the man behind this tragedy. They will not say if he had a connection to Keyes. His identity is also unknown, authorities for now are calling him a John Doe.

The CBI is leading the investigation supported by Park and Jefferson Counties.

They promise answers to a grieving community.

"We will be taking steps that our investigation is thorough and prompt," said CBI investigator Steve Johnson. "We will leave no stone unturned."