Surveillance video shared on social media of a shooting inside a Spring Garden pizza shop last week appears to contradict portions of the initial account shared by police, including the assertion that the shooting victim was shot after he tried to strangle the mother of the teenager who ended up firing on him.

The 28-second video instead shows the would-be robber forcefully reaching for the register — not the cashier — in an apparent attempt to steal money. Within seconds, a 14-year-old behind the counter pulled a gun from his waistband and fired from point-blank range, the video shows. Police had initially said the teen grabbed the gun from beneath a counter.

Authorities on Thursday declined to comment on the apparent discrepancies, except to say their initial account was based on preliminary information and that the episode remained under investigation. In general, preliminary reports from police tend to be based on early interviews with witnesses or victims as investigators seek to gather additional forensic or video evidence.

The shooting attracted attention in part because of the dramatic notion that a teen had intervened in an attack on his mother at the pizza parlor at 15th and Spring Garden Streets. Surveillance video of the incident has since been posted by Reddit and had attracted more than 12,000 comments by Thursday.

Authorities have not identified the teen, his mother, or the robbery suspect, and have not said if anyone has been charged.

Bold Pizza was open for business Thursday but a manager declined to comment, saying employees and police are still “trying to figure out what happened.”

According to the initial police account, the robbery suspect entered the shop around 9:47 p.m. on Dec. 9. The surveillance video shows the man hand cash to the cashier before he reaches over the counter and tries to take money from the register.

In their initial account, police said the man had “started to strangle” the cashier, but the video only shows the man reaching for the register.

Police also initially said the teen — who they said was the 14-year-old son of the woman working the register — had grabbed the firearm from under a countertop. But the video shows he pulled the gun from his waistband, then shooting the robbery suspect in the face.

A bystander was just feet away when the shot was fired.

The man struck by the bullet ends up slumped over the cash register as the video ends. Police said he ultimately made his way to the nearby Spring Garden stop of the Broad Street Line, where officers found him and took him to Jefferson Hospital in critical condition.

It was not clear Thursday if he remained hospitalized or had been released.

Staff writer Anna Orso contributed to this article.