President Obama’s announcement that Osama bin Laden had been killed in a U.S. raid in Pakistan disrupted prime-time broadcasts in varying degrees in different time zones, and ensured that final results won’t be known for a while, TVbytheNumbers.com reported.

But it appears that ABC will come out as the top network for the night, in a close race. Preliminary figures show ABC averaging a 2.5 rating in the 18-49 demo, ahead of NBC’s 2.4, Fox’s 2.1 and CBS’s 2.1. CBS has the lead in total viewers with an average of 9.5 million to 8.7 million for ABC, 7.4 million for NBC and 4.6 million for Fox.

Hourly results are expected to change, but in preliminary numbers at 7 p.m. ABC’s "America’s Funniest Home Videos" had a 2.05 average in the 18-49 demo for the hour, topping CBS’s "60 Minutes" with a 1.5 average. NBC’s "Dateline" had a mean score of 1.3 in the 18-49 demo for the hour.

The 8 p.m. hour was won by ABC’s "Extreme Makeover" with a 2.7 average in the 18-49 demo, while Fox’s "The Simpsons" at the top of the hour had a 2.9 in the same demo. CBS’s "The Amazing Race" averaged a 2.5 in the 18-49 demo, and NBC’s finale of "America’s Next Great Restaurant" had a mean score of 2.0.

At 9 p.m. ABC’s "Desperate Housewives" had a 3.0 average in the 18-49 demographic for the hour, while hour one of "Celebrity Apprentice" was right behind it with a 2.95 average. CBS’s "Undercover Boss" averaged a 2.05 in the 18-49 demo for the hour.

At 10 p.m. "Celebrity Apprentice’s" second hour had a 3.45 average in the 18-49 demo, ahead of CBS’s "CSI: Miami" with a 2.15 and ABC’s "Brothers & Sisters" with a 2.05.