"We've seen all the reports and we don't have an official statement yet. This will be coming later today" a state department official told PTI.
"We obviously want to confirm Bhutto's welfare. At this time we have seen a lot of reports - from that she is dead to that she was not at the rally" the official added.
"We are condemning the attack and we are saying that the attack shows that there are still those in Pakistan who are trying to undermine reconciliation and democracy there" the official said.
The White House is also expected to issue a formal statement on the developments in Pakistan. President George W Bush is in Crawford, Texas where he has been kept informed of the goings on.