A suspect has been arrested after he and his 100-pound dog allegedly attacked four people overnight, Toronto police say.

At around 2:45 a.m., police responded to reports of a carjacking in the area of Third Street and Lake Shore Boulevard West.

Police say a man ordered a rideshare vehicle and when the driver arrived the man attacked the driver with his hands.

The man then ordered his dog to attack the driver, police say.

The suspect then fled with the driver’s red car.

The victim, a man in his 50s, was taken to hospital in stable condition.

Almost two hours later, police responded to a robbery in the Norris Crescent Parkette, near Humber Bay Park, at around 4:35 a.m.

Police say a man and woman were riding their bicycles through the park.

"They stopped to take pictures when they were approached by a man with a dog. The man sets the dog to attack the woman, she's in hospital recovering from her injuries. He takes her bicycle, sets the dog to attack the man. I don't believe there was an attack there but there was an attempt," Const. David Hopkinson told CP24 Saturday morning.

The woman is in hospital in stable condition.

Police say the dog also attacked another nearby person in the park. Their injuries are unknown.

A short time later, police say a man who was sleeping on his boat at the nearby Etobicoke Yacht Club heard commotion outside.

The man saw that the suspect, who was with his dog, was attempting to steal the dinghy from his boat.

The suspect and his dog then fled the scene.

The man was not injured.

Police say the same man is believed to be responsible for all four attacks.

"(This is) disturbing because the seriousness of these injuries and these attacks and they're somewhat random, that's disturbing. There are a lot of people...that trust people approaching them with a dog and that breaks that trust," Hopkinson said.

The dog is described as a 100-pound, brown pit bull or mastiff.

At around 10 a.m. on Saturday, police said the suspect was located and taken into custody, and his dog was given to Animal Services.

Police say this is an ongoing investigation and are asking anyone with information to contact them.