Authorities responded to C C Diamonds at 3240 Wilshire Boulevard, just west of Vermont Avenue, at about 11 a.m. after someone reported hearing screaming and glass breaking.
According to the Los Angeles Police Department, a parking attendant was severely beaten by the suspects. He was rushed to Los Angeles County USC Medical Center. He was in critical but stable condition Tuesday afternoon.
A 27-year-old female suffered lacerations during the robbery, but she was expected to be OK.
The suspects fled out of a rear exit and carjacked a driver, then drove away in a white van. The van was last seen driving southbound on Vermont Avenue.
The victim of the carjacking did not resist and was not injured.
"The parking-lot attendant was viciously attacked by these two male blacks as they were fleeing from the location. They came out after the attack. They ran out, they attempted to take a car from a female Korean in her 30s. They broke out her window -- again, very vicious," said LAPD Captain Tina Nieto.
The suspects remain on the loose. Suspect descriptions were not immediately available. Police said the pair should be considered armed and dangerous.
Streets in the area were briefly shut down while police investigated.
Police said the thieves did not get away with anything from the store.
Anyone with information related to the incident should contact the LAPD at (877) LAPD-24-7.