SANTA CLARA, Calif. -- The San Francisco 49ers placed receiver Ricky Pearsall on the reserve/non-football injury list Monday, two days after he was shot in the chest during a robbery attempt in San Francisco.

The NFI designation means Pearsall must miss at least the first four games of his rookie season as he recovers. San Francisco signed offensive tackle Brandon Parker to a one-year deal to fill the open spot on the 53-man roster.

Pearsall was shot near San Francisco's Union Square on Saturday afternoon after a 17-year-old male from Tracy, California, attempted to rob him, resulting in a struggle between the two, according to the San Francisco Police Department. Both Pearsall and the suspect were shot during the struggle.

After Pearsall was taken to San Francisco General Hospital, police announced that he was in stable condition. He was upgraded to fair condition Sunday morning and released from the hospital soon after, less than 24 hours following the shooting.

Pearsall's mother posted on social media Sunday morning that her son had been shot in the chest with the bullet exiting his back and missing vital organs. Before the shooting, Pearsall had participated in an autograph signing at an event center before going to Union Square, ABC7 in San Francisco reported.

According to the police, Pearsall was walking alone shortly after 3:30 p.m. local time Saturday when the suspect attempted to rob him with a gun at the corner of Geary and Grant streets. The San Francisco Fire Department said a 911 call came in at 3:38 p.m. PT, with police and emergency personnel arriving soon after.

San Francisco Police Chief William Scott said the suspect was arrested right after the shooting. The initial investigation indicated he was acting alone "as far as we know," Scott said, adding that police would continue to scour the many surveillance cameras in the area as the probe continues.

Scott said there was "no indication" that the suspect had targeted Pearsall because he is a professional football player and added that there was one gun involved, with multiple shots fired.

District Attorney Brooke Jenkins said a charging decision on the suspect, whom she noted is a juvenile, would be made Tuesday or Wednesday.

The 49ers selected Pearsall with the No. 31 pick in April's NFL draft. He'd been slowed in training camp by shoulder and hamstring issues but returned to practice last week wearing a blue "no contact" jersey.

In signing Parker, the Niners added insurance as they continue to work on adjusting left tackle Trent Williams' contract. Williams has been a holdout during camp as he seeks a raise and guarantees on the contract he signed with the team in 2021.

Parker was with the Niners throughout the preseason, working as a backup to current starting offensive tackles Colton McKivitz and Jaylon Moore. The 49ers open the season at home on Sept. 9 against the New York Jets.