A car bomb outside the US consulate in Karachi has killed a US Foreign Service officer and at least four other people.
Afterwards in the Indian capital, New Delhi, President George W Bush said 'terrorists and killers' would not stop his scheduled visit to Pakistan.
The blast came less than 48 hours before Mr Bush was due to hold talks in Pakistan on Saturday, though he is not expected to visit Karachi.
The explosion in Pakistan also injured at least 35 people, including three security guards at the main entrance to the consulate.
President Bush yesterday began a three-day visit to India.
Today, the two countries concluded an agreement on civilian nuclear co-operation.
Mr Bush has described India as a natural ally of the US and said he hoped to forge a new strategic partnership with Indian Prime Minister Manmohan Singh.
The agreement, the highlight of the visit, commits Washington to seek approval from Congress and the countries of the Nuclear Suppliers Group to lift restrictions on sharing civilian nuclear technology with India.
