|Source: WOAI TV|
Nobody seems to know for certain, but WOAI's John Gerard reported that it was probably what is known as an "April fireball."
"I spoke to our astronomer expert Bob Kelley with the Scobee Planetarium," wrote Gerard, "and he explained that it was a phenomenon called 'April Fireballs.' Chunks of meteors enter and burn up in our atmosphere. The fireballs are brighter than a shooting star and can happen at any time of the day. For reasons astronomers don't fully understand, they occur in early April."
What is an "April fireball?" According to the American Meteor Society, "A fireball is another term for a very bright meteor, generally brighter than magnitude -4, which is about the same magnitude of the planet Venus in the morning or evening sky. A bolide is a special type of fireball which explodes in a bright terminal flash at its end, often with visible fragmentation." See their Fireball FAQ page.
Annual Meteor Showers (saguaroastro.org)
Meteor Activity Outlook for April 7-13, 2012 (amsmeteors.org)