A collision between two buses on southbound Interstate 5 injured 18 people and closed express lanes in Seattle for hours Monday morning.  Crews responded just before 8 a.m. after a pair of buses were reported to have collided on southbound I-5 near Mercer Street.  The buses were not the property of the Navy but were carrying Navy personnel, Washington State Patrol's Rick Johnson said Monday morning. The Washington State Patrol said the crash occurred when one bus slowed down but the bus following the first one didn't slow down in time, causing the two to collide. The two buses were carrying 40 or more sailors.  According to the Naval Surface Forces, the sailors were traveling from Naval Station Everett to their ships which are currently under maintenance on Harbor Island. The sailors are stationed aboard the USS Chosin, USS, Cape St. George and USS John Paul Jones. Seattle Fire reported that crews treated 18 people at the scene, all of whom were in stable condition. Harborview Medical Center confirmed the hospital received 10 patients beginning at 8:10 a.m. Monday as a result of the crash. There were seven men and three women between 20 and 30 years old. According to the Navy, three other patients were transported elsewhere for treatment of minor injuries.  All patients taken to Harborview Medical Center were discharged by Monday afternoon. The crash was originally called a "mass casualty event," which is something the hospital prepares for.  “We put into place the protocols we have which immediately allows us to clear the emergency department of other patients,” said Mark Taylor who is the senior associate administrator at Harborview. READ THE FULL STORY: https://www.king5.com/article/traffic/i-5-bus-collision/281-af3a0a69-65e2-4c70-86f0-bc2f44cdef3a