Toronto police are investigating a violent robbery and assault that occurred Tuesday morning, which police believe may be part of a string of similar attacks.

On Tuesday morning, an escort was assaulted and robbed on the 12th floor of the Quality Suites Toronto Airport at 262 Carlingview Dr., near Highway 427 and Dixon Road.

A 22-year-old escort was in one of the hotel’s room at 5 a.m. when she heard a knock at the door, police said at a news conference Tuesday afternoon.

She looked through the peep hole and saw one man, the client she was expecting, so she opened the door, police said.

Immediately, three other males appeared and pushed her into the bathroom, where she was allegedly hit on the head.

Police said two of the men sexually assaulted the escort before taking her money, clothing and identification.

The hold-up squad is working with other police departments as part of an ongoing investigation. There have been a series of similar reports collected between October and December, police said.

Four other attacks have happened at hotels in the area, and follow a similar pattern: a fake client appears at the door, then three other men rush in and beat the escort with a television remote or their hands. No guns have been seen during the attacks.

"We believe these suspects are targeting ladies that are advertising in the escort business, and then pretending to be customers," Staff Insp. Mike Earl said.

Police are searching for four suspects in connection with the incident.

The first has been described as a white, 5-foot-7 man believed to be in his early 20s. Police are also looking for three black men, between the ages of 19 and 25, who were wearing dark clothing at the time of the incident.

As part of their investigation, they will be reviewing surveillance video recorded at the hotel and businesses in the area, Earl said.