Unsure what type of animal it was at first, he snapped a picture.
"I was pretty surprised it was this close to us,” Lucas explained.
He scared it off, but it came back when he wasn't looking. The next thing he knew, the coyote had pounced on his daughter. He rushed to save her.
"I immediately reacted,” Lucas recounted. “Jumped off the ladder. The animal ran off and I chased it away."
Lucas lives near Swenson Park and wildlife sightings are pretty common in the area. But this is the first time he's come across a coyote.
Sightings appear to be up across the region. Last week, a Bainbridge Island family says, a coyote attacked and killed their dog.
Earlier in November, a KIRO 7 photographer recorded a video of coyotes in Seattle's North Beach neighborhood while investigating reports of a coyote that attacked a cat.
But attacks on humans are rare.
Lucas is just thankful his little girl is OK.
"It could have been much worse,” he said. “It could have really harmed her or worse, killed her."
Snoqualmie police think someone is feeding the coyotes, prompting them to be less skittish around people. People are advised to never do that and to make sure their trash is covered or not take it out until trash day.
Police say they've had 10 reports of coyotes since Friday.