A woman was sexually assaulted at a downtown Minneapolis bar above a posh dining spot after she left the bathroom, and the man was stopped from going further by a security guard who happened to be walking by, according to a criminal complaint.

Mainza L. Malambo, 21, of Eagan, was charged Monday in Hennepin County District Court with third-degree criminal sexual conduct in connection with the alleged assault early Saturday at the rooftop bar over Seven, a steakhouse and sushi bar at 700 Hennepin Av. S.

Malambo did not know the 35-year-old woman he targeted about 1:40 a.m., according to police.

Seven’s chief manager, David Koch, said Wednesday that he and police reviewed the incident captured on video surveillance and it shows “you’ve got two people who appear to be making out in a corner, [but] nobody seems to see this woman is in distress. … It’s very difficult to know what is happening.”

Koch said his security guard asked the woman what was going on.

“She got her set free,” he said. “ … I’m proud of our staff, and our [security guard] intervened on her behalf as quickly as she did.”

Malambo’s mother, Grace Chiluba, said she spoke with her son and has a “vague understanding” about the accusations. She said she told him, “ ‘I’m sorry you are in such a predicament.’ ” She said he was arranging legal representation by a public defender.

Chiluba said her son is currently serving in the Minnesota National Guard in the Twin Cities.

According to the criminal complaint:

The woman told police that Malambo stopped her as she came out of the bathroom and “pinned her in a corner of the hallway.”

Malambo started kissing the woman, prompting her to try in vain to push him away. While she was still trapped in the corner, Malambo sexually assaulted her, according to the complaint.

A security guard walking by asked the woman whether she was OK. She “expressed with her eyes that she was not and mouthed ‘no’ to the guard,” the complaint read.

Malambo stepped away from the woman and revealed that he exposed himself. Malambo then fled.

The guard pointed out Malambo to police officers working part-time at the bar. The officers stopped Malambo at the door as he was trying to leave and arrested him.