The Dec. 21 blast by a bomber apparently dressed in an Iraqi military uniform killed 22 people and wounded 69 others. Sanchez, 19, knew several of the injured.
"He felt very lucky and grateful to have walked away from that," said his wife, Tiffany, 19. "I don't know what else he saw over there, but that's the first tragedy in Mosul I heard that was so close to him."
She had to wait until the day after Christmas for a phone call from her husband assuring her that he was all right. Sanchez asked about family members back home, and the couple talked about being apart on New Year's Eve, their first wedding anniversary.
It was the last time Tiffany Sanchez spoke to her husband.
On Dec. 29, Oscar Sanchez was killed during a two-stage attack by insurgents. He was at an observation outpost when a suicide bomber drove a truck into the Army compound with an estimated 1,500 pounds of explosives. As a patrol responded with aid, a second bomber blew up a car filled with explosives. Sanchez died later that day, and 14 others were injured.
In a written tribute to the fallen solider, Lt. Col. Eric Kurilla said that although Sanchez could have ducked for cover to avoid the shrapnel, he instead stood his ground and continued firing at the driver of the truck, forcing him to detonate the vehicle before it crashed into a building, thereby saving fellow platoon members.
"Pfc. Sanchez gave his life so that others may live," Kurilla wrote. "It is incredibly humbling to serve in the presence of such men."
Tiffany Sanchez said she considered her husband to be very brave just for joining the military after the Sept. 11 terrorist attacks.
"Nobody understands why their loved one has to be the one" to die, she said. "To me, he was an American hero and he will be my personal hero, forever."
Oscar Sanchez was raised by his father, Santos, after his mother died when he was 11. Relatives said Sanchez had an outgoing personality and enjoyed video games, radio-controlled cars, basketball and skateboarding.
During high school, after working six months at a Burger King, he gave up his job and enrolled in alternative education classes so he could stay home and help care for his 25-year-old brother, Juan Antonio, who has Down syndrome
"He was an awesome person. He never let anyone down when they needed him," said his cousin, Stella Padilla. "We lost a good one. Like they say, 'God always takes the good ones first.' "
Sanchez joined the Army shortly after graduation and began active duty in October 2003. He took his basic training and advanced individual training at Ft. Benning, Ga.
While in Georgia, he proposed to Tiffany in a letter home. He apologized for not being present to get on one knee, she said, and stated that he wanted to tie the knot during a two-week leave at the end of the year.
Sanchez was then assigned to Ft. Lewis, Wash., just south of Tacoma, and took his young bride with him. They arrived on Valentine's Day 2004, and after the 12-hour drive from Modesto, Sanchez surprised his wife with candy and a teddy bear.
The couple lived together in an apartment near the base until last fall, after Sanchez was notified that he would be shipped to Iraq in October. Tiffany Sanchez returned to her parents' home in Salida, Calif.
She said she usually got a phone call from Sanchez each week after he arrived in Iraq. She was ready to ship him a package of magazines, toiletries and pretzels covered in white chocolate, his favorite snack, on the day a lone Army official came to her door.
"He hadn't even said a word, he was still standing outside, but I burst into tears and was screaming.... I knew something bad had happened," she said. "To me, I thought my husband was invincible. You never think anything is going to happen to someone you love so dearly. And when it does, it hits you very hard."
Sanchez was assigned to the 1st Battalion, 24th Infantry Regiment, 1st Brigade, 25th Infantry Division's elite Stryker Brigade Combat Team at Ft. Lewis.
He had earned the National Defense Service Medal, Global War on Terrorism Medal and Army Service Ribbon. After his death, he was awarded a Good Conduct Medal, Purple Heart and Bronze Star, which is given for valor or service.
In addition to his wife and father, Sanchez is survived by siblings Griselda, Jorge, Juan Antonio and Leonardo.
In addition to a memorial service held Friday at Ft. Lewis, Sanchez is scheduled to receive a funeral with full military honors Tuesday at Saint Stanislaus Catholic Church in Modesto.