1.   With machine bolts use hex nuts with hex heads and square nuts with square heads.

2.   A fire spokesman described the bomb as a butane canister with nails and hex nuts, which peppered the site.

3.   A fire spokesman, speaking on condition of anonymity, described the bomb as a butane canister with nails and hex nuts, which peppered the site.

4.   Bombs fashioned from gas canisters crammed with nails and hex nuts have been the hallmark of all six bombings or attempts.

5.   Gas canisters packed with nails and hex nuts have been the signature devices used in the other bombings and attempts.

6.   The explosion, from a gas canister loaded with hex nuts, was among at least eight bombings or attempted bombings since July.