I couldn't find an official source but found Santa Monica news website with additional information.

tl;dr:

Kid missing:

• Image

• Jaden Giarraputo

• Male, White, 3 years old, 3 feet tall, 35 lbs.

• Last seen Dec 11, 2016 in Simi Valley, CA in a Blue 2015 Kia Soul CA plate #7JEX347

• wearing a gray t-shirt, blue shorts, and blue shoes

Suspect:

• Image

• Anthony Giarraputo

• Male, White, 31 years old, 5'9", 220 lbs., brown hair and eyes

• Last seen wearing gray shorts and driving a Blue 2015 Kia Soul CA plate #7JEX347

Amber Alert Active Counties:

• Kern

• Los Angeles

• San Louis Obispo

• Santa Barbara

• Ventura

Note: I can't vouch for the accuracy of this source. The date says it was posted tomorrow.

Source: http://www.smobserved.com/story/2016/12/12/news/amber-alert-issued-for-jaden-giarraputo-simi-valley-kia-soule-license-plate-7jex347/2366.html