HOOKSTOWN, Pa. — Authorities are searching for a missing 4-year-old boy with a heart ailment.

State police in Beaver County said Wyatt Smitsky was last seen by his family outside their Greene Township home shortly after 7:30 p.m. Friday.

Police said the boy might have just walked away from his home. They said they are especially concerned because he has a congenital heart defect that requires medication.

Almost 200 emergency personnel and volunteers searched dense woods with the help of dogs until 3 a.m. today. Authorities also have been using ATVs and a helicopter with infrared sensors to look for the boy.

The boy is described as about 4-feet-tall, with a skinny build and blond hair and blue eyes. He was dressed in a military-style brown T-shirt, blue shorts and Spiderman flip-flops.