MONTREAL—An American family has filed a $3.9-million lawsuit against the Marriott hotel chain after a father and his toddler drowned at one of the company’s Montreal properties three years ago.

The family’s Superior Court filing, made public Tuesday, says the hotel is responsible for the deaths because its pool area was allegedly unsafe, improperly supervised and lacked video surveillance or an emergency alarm.

William Tchouamou Ganjui and his two-year-old son, Menelik, allegedly fell into the deep end of the pool at the Residence Inn by Marriott in downtown Montreal on April 20, 2016.

The 37-year-old father was pronounced dead that day while the toddler died a few days later in hospital. Ganjui’s widow, Chimene Mbague Nandjou, is seeking $3.9 million on behalf of the estates of the two victims, herself and her two surviving daughters.

Her late husband, a computer programmer, was the sole breadwinner in the family.

The lawsuit states Ganjui and his three young children — Menelik, Aurellia and Wilma — had visited the hotel pool together. The father was holding the toddler in his arms when he “slid into the deep end of the pool.”

Aurellia and Wilma allegedly threw a life buoy to Ganjui, who “hung Menelik’s arm around it before (Ganjui) went under and sank to the bottom of the deep end.”

If the hotel “had provided a lifeguard and/or other safety personnel at the pool at the time of the deaths ... or monitored the pool ... it is more likely than not that Menelik and William could have been saved with timely assistance,” the lawsuit claims.

It further alleges that shortly after the deaths, the hotel pool was staffed with a full-time lifeguard and monitored by cameras.

Marriott International Inc. did not immediately respond to a request for comment.

Serge Dube, a Montreal lawyer for the family, said Wednesday the lawsuit had been filed but his clients had 60 days to serve it.