MONROE, Mich. -

Federal authorities have taken over the investigation into who planted a bomb in a Michigan family's van that exploded Tuesday night.

Bureau of Alcohol, Tobacco, Firearms and Explosives Detroit office spokesman Donald Dawkins said the "sophisticated" explosive device had a timing mechanism.

It exploded at about 5:30 p.m. while 42-year-old Erik Chappell and his 11-year-old and 13-year-old sons were on Elm Street near I-75 in Monroe. Chappell, an Ohio-based attorney, was with his sons for football practice at a Monroe junior league for fourth, fifth and sixth graders.


The three were at St. Vincent Medical Center in Toledo, Ohio, in serious condition. Chappell was released from the hospital Wednesday, but his sons were still there.

?There was a lot of power behind it. The victims are very fortunate and very blessed to be alive,? Dawkins said.

Witnesses flooded 911 with calls about the explosion and fire. Chappell called 911 just moments after the explosion.

"My car blew up with two kids. You have been called about it already but I am calling to tell you what's going on with the boys," Chappell told the 911 dispatcher. "I've got two significant leg injuries. One to his bottom-left leg and one to his buttocks, chewed up pretty good ... they are bleeding. I need someone here now."

Local 4 cameras were rolling while the van was towed to a garage. Its windows were blown out and only a charred metal shell remained.

?We take everything seriously, but when you have children involved, it really hits home,? Dawkins said. ?It?s a horrific crime.?

Dawkins said there is a $10,000 reward being offered for information in the case. Tips can be left at 800-ATFBOMB or 313-222-3400.

Chappell is well known attorney for divorce and business dispute cases.

Fellow attorney John Gillooly is opposing him in a civil case in Detroit and calls Chappell a tough advocate and dedicated father.

?He always wanted to make sure that his business day was done at the appropriate time so he could get back to his kids and enjoy life with his kids,? Gillooly said.

Chappell lives in LaSalle, Mich., which is about five miles from where the bomb exploded.

Monroe is located about 35 miles southwest of Detroit and 20 miles northeast of Toledo.