Bevacizumab, Erlotinib and 5-Fluorouracil With External Beam Radiation Therapy in Locally Advanced Rectal Cancer

* All participants will receive the following drugs: 5-fluorouracil (5-FU) given as a continuous 24-hour infusion; Bevacizumab given intravenously; erlotinib given orally at home. In the Phase I portion, we are looking for the highest dose of erlotinib that can be given safely in combination with the 5-FU, bevacizumab and radiation therapy. Therefore the dose of erlotinib may not be the same for each participant. The dose will increase until we find the highest dose without causing serious or unmanageable side effects. * Study treatment is given as an outpatient and consists of 14 day cycles with a total of 3 cycles. Patients will be given all three study drugs and radiation therapy on a monday (unless a monday falls on on a holiday). This will be day 1 of the first treatment cycle. 5-FU is given continuously days 1-14. Bevacizumab is given on day 1. Erlotinib will be given on days 1-14. Radiation therapy will be performed on Days 1-5 and 8-12. * The following tests and procedures will be performed weekly while participants are receiving study treatment: physical examination, measurement of vital signs, height and weight; performance status; blood work, urine sample. * At the end of treatment the following tests will be performed: physical examination and measurement of vital signs; performance status; blood work; CT scans of chest, abdomen and pelvis. Patients will also be evaluated for surgery at this time. Patients will be followed every three months for the first three years after surgery, then every 6 months for the next two years.