Apollo 13 Transcript available online.

02 07 55 20
Jack Swigert (CMP)
I believe we’ve had a problem here.
02 07 55 28
Jack Lousma (CAPCOM)
This is Houston. Say again, please.
02 07 55 35
Jim Lovell (CDR)
Houston, we’ve had a problem. We’ve had a MAIN B BUS UNDERVOLT.

(Tom said, “Houston, we have a problem.”)