This site:
http://shopwornangel.imaginarynumber.net/flight-log/
for the B-26 344th BG has the following:
Mission 30: July 28, 1944 2ND FOR DAY
TARGET:
GAS AND OIL DUMP
LOCATED: SENONCHES
BOMB LOAD: 28 – 100LB.
DAMAGE: NONE
FLAK: WEAK INACCURATE
ESCORT: P38
Senonches is NW of Chartes. Possibly other groups were involved.