An urgent care center was a type of walk-in medical facility, generally smaller in size and scope than a hospital. There were many urgent care centers dotted around the city of Los Angeles, helping with cases requiring immediate medical attention, though not equipped to deal with major surgery.
On Day 2, after Jonathan Wallace was shot in the neck by Peter Kingsley's men, Jack Bauer took him to an urgent care center in North Hollywood. He ordered Dr. Spire to perform emergency surgery on Wallace, but the doctor was unable to save his life. Jack then noticed in X-rays of Wallace that he had a computer chip implanted in his body, which Jack removed with a scalpel. ("1:00am-2:00am")
Kingsley's men tracked the location of the chip to the care center, and Jack told Yusuf Auda and Kate Warner to take it to CTU while he distracted the men. Kate and Yusuf escaped but Jack was captured and tortured in a back room of the care center. His heart stopped due to the intense torture, but he was revived with the help of Dr. Spire. Jack then escaped from his captors, and made his way out of the facility. ("2:00am-3:00am", "3:00am-4:00am")