Guess – that’s two!

1) Boeing B-17F-27-BO Fortress
41-24631 crashed 5 mi S of Walla Walla, WA Jul 15, 1942. All 5 crew killed.
http://home.att.net/~jbaugher/1941_4.html

2) Boeing B-17F-50-BO Fortress
42-5367 crashed Feb 11, 1943 in mountains SE of Walla Walla, WA.
http://home.att.net/~jbaugher/1942_1.html

‘On 2-11-43, the B-17F # 42-5367, while flying in instrument conditions, collided with rising terrain “17 airline miles east of Walla Walla, struck a ridge at approximately 6,000 feet msl near Table Top Mountain at 1115.” Ten crewmembers were killed. A detailed summary of this accident can be found on Page 270, Volume I, FATAL ARMY AIR FORCES AVIATION ACCIDENTS IN THE UNITED STATES, 1941-1945.’
http://www.websitetoolbox.com/tool/post/pacaeropress/vpost?id=1788376

newspaper scans
http://www.websitetoolbox.com/tool/view/mb/file?username=pacaeropress&id=552910