. >> reporter: november 14th, gunman in tahoma county, california fires 30 rounds into an elementary school. te police, they discovered earlier he murdered five people unseale residence. we believe that's probably what started this whole event. >> reporter: what starts these events is always the subject of detective work, community secondssest question why is this happening more frequently. this year, 18 school shootings. there were seven by this time last year. since 2013 the school shootings 16s risen with exception being acceptable or normal. as a sign of the times more scs 3 of sool districts conduct active shooter drills. though 19 states require them. cbs news law enforcement analyst, paul violas. >> this is something so prevalent, rehearsed part of curriculum. making sure we minimize the ar inhappening at a rate of one a week. some are accidental or suicide where the only victim was the shooter. jeff. >> done dahmer, thank you very much. we will continue to watch what is hatch penning in parkland, .g the investigation with jeff pegues. more on the shooting later in the broadca

. >> reporter: november 14th, gunman in tahoma county, california fires 30 rounds into an elementaryl. after the gunman was killed by police, they discovered earlier he murdered five people including his wife. >> we located her dead body unsealed under the floor of the residence. we believe that's probably what started this whole event. >> reporter: what starts these events is always the subject of detective work, community second-guessing and familial agonizing. perhaps the biggest question why is this happening more frequently. this year, 18 school shootings. there were seven by this time last year. since 2013 the school shootings has risen with exception being 2016 when there were 48. only, as if that was in any way acceptable or normal. as a sign of the times more the try the deoderant saving millions of clothes. degree ultraclear black + white. no yellow stains on white clothes. no white marks on black clothes. try degree ultraclear black + white. it won't let you down. aww thanks for loading, sweet... oops. oh burnt-on gravy? gotta rinse that. nope. no way. nada. really? dish i