ST. LOUIS, Mo. -- A St. Louis County man killed his two sons before turning the gun on himself, police said Saturday.

Early Saturday evening, St. Louis County Police issued an Amber Alert for two area children believed to have been abducted by their father.

Christopher Cadenbach, 43, spent Saturday with his two children, Ethan Cadenbach, 5, and Owen Cadenbach, 4. He reportedly visited his estranged wife as well as his mother earlier in the afternoon, including a trip to a park.

Cadenbach's mother contacted police after he began to act strangely. He talked about "not being taken alive", including references to suicide by cop. Prior to an Amber Alert being issued around 6:30 p.m., a $100,000 domestic violence warrant was issued for his arrest.

Cadenbach was last seen with his children near 343 Rauhut Ave. in south St. Louis County near Lemay in a dark grey 2006 Ford Focus. The Amber Alert was issued shortly thereafter.

Just before 8 p.m., a Cliff Cave Park Ranger spotted the Ford Focus and approached Cadenbach with the assistance of other officers. As they got closer to Cadenbach, he shot and killed his children, before turning the gun on himself.

Sunday, community members held a vigil in honor of both Ethan and Owen.

“Just like any average four and five-year-old boys,” said Sarah Sartorius after a candlelight prayer service at St. Paul Catholic Church in Fenton.

Sartorius was their aunt. More than 100 people showed up for the prayer service organized by a group of mothers who know the Candenbach family.

“Enthusiastic and full of energy. Always fun-loving,” she said of the brothers.

Sartorious said what makes this unspeakable crime even harder to understand is the way the man police say killed them also seemed to love them.

“Their father was actually a really good father to them,” said Sartorius. “That's why we're having a really difficult hard time trying to figure out why he did this."

A GoFundMe page has been setup for funeral expenses for both Ethan and Owen Cadenbach. To help donate, click here.

Photos: Amber Alert issued for two children.