A man was arrested after an undercover detective watched him sexually abuse a young girl during a live Internet chat from the suspect's home, police said Thursday.

The man was arrested and the preschooler rescued two hours after the attack, in what Toronto police's child exploitation unit said was its first case of observing a live assault.

Police said they would not disclose whether the suspect and victim were related, in an effort to protect the identity of the child, who has been put in the care of family members.

"My first reaction was that I wanted to reach through the monitor and grab the child," said Detective Paul Krawczyk, the undercover officer who witnessed the violent attack on Sunday. "It raised the hair on the back of my neck."

He alerted police in St. Thomas, a city in southwestern Ontario where police believed the man lives, and they were able to track him down in two hours.

"To see this child and look that child in the eyes and realize that the child was live somewhere, being abused, we had had to save the child right then," Krawczyk told a news conference. "The minute we realized what was happening, we went as fast as we could."

Krawczyk belongs to Toronto's elite Child Exploitation Section, acclaimed for its work tracking down child pornographers on the Internet. Microsoft Corp. teamed up with the detectives last year to launch a software program designed to help police forces around the world hunt down child porn Internet traffickers.

"The message to all pedophiles, and people who want to sexually exploit children on the Internet is that we are on the Internet 24/7, we know where you are and we will find you," Krawczyk said.

He said the 34-year-old man was not identified to protect the girl. He declined to say whether the man was related to the girl, but did say the man was arrested in his own home.

Krawczyk said the girl was safe with other family members and getting medical care.

The man's bail hearing was set for Nov. 7 and he faces 10 charges of sexual assault and the making, possession and the distribution of child pornography.

Krawczyk, who was posing as an online pedophile, said he established a relationship with the man in an Internet chat room for pedophiles in January. After gaining his trust, the suspect on Sunday sent still images recorded on a Web cab, which were transmitted "real time" to a private site, a location that Krawcyzk said he could not disclose.

"I can't get into exactly what the program is," Krawcyzk told the AP. "But you see the images immediately. I was talking with him and, I can't get into the details of what were in the pictures, but I knew that it was happening live."

He also said he could not say how he tracked the man down to St. Thomas, but said it was not until Sunday, when he observed the live assault, that police had cause to arrest him.

The Child Exploitation unit is credited with helping Florida police locate a young girl who had appeared in a series of sexually explicit photographs taken at a Walt Disney World hotel.

Krawczyk said this type of Internet crime was growing as webcams and digital cameras become cheaper and easier to use.

"Ten years ago there weren't that many digital cameras around," he said. "Now you can take these images and download them on your computer and have them halfway around the world in minutes."