Families of the victims of the September 11 attacks gathered on Capitol Hill Tuesday to demand that an independent commission investigate why the U.S. government failed to detect and prevent the attacks.

About 200 family members of those who died in the attacks nine months ago demonstrated outside the U.S. Capitol building to press for an inquiry by an independent commission.

Among them was Mindy Meinberg, who lost her husband on September 11. Ms. Meinbuerg said, "We would like to call upon the country's foremost experts to lead the investigation. Let no stone remain unturned. We are asking you, America, to stand behind us. Please pick up the phone, call your senators; call your congressmen, tell them you want to be safe. Tell them you want an independent investigation. We do not ever want to ask the question again, 'How could this have happened?'"

Ms. Meinberg believes the joint House-Senate Intelligence Committee probe into the September 11 attacks is not enough. That committee resumed its closed-door hearings Tuesday.

Victims' families were joined at the rally by Democratic members of the House and Senate. Among them, Senator Chuck Schumer of New York who said, "Why are we afraid of the truth? It must come out."

But Republican lawmakers and President Bush are opposed to the creation of an independent commission. Senate Minority Leader Trent Lott of Mississippi said, "I think the most important thing is that the focus be in the intelligence committees. They have spent months getting ready. They have got 200,000 pages of documentation now. They have a staff in place. They are going forward with hearings. That should be the focus."

Opponents of a commission argue that an independent probe would take time away from officials who are busy fighting the war against terrorism. Those officials are expected to be called to testify before the joint intelligence committee in the coming weeks.