The older of the two Boston bombing suspects bought two mortar kits from a New Hampshire fireworks store in February, although the amount of gunpowder the kits would have supplied wouldn’t have been enough on its own to detonate the bombs, company officials said Tuesday.

Tamerlan Tsarnaev bought two “Lock and Load” reloadable mortar kits containing 24 shells each on the evening of Feb. 6, said April Walton, the manager of Phantom Fireworks in Seabrook. He paid $200 cash but scanned his driver’s license into the company’s computer system as required by store policy.

“We have a bank of computers at the front end where we greet everyone and hand out safety flyers,” she said. “He was just an average customer. … He signed in, walked around and purchased the kits with cash.”

Walton wasn’t in the store at the time but said the employee who handled the sale described it as a routine transaction.

Tsarnaev, 26, and his younger brother, Dzhokhar, 19, are accused of setting off the bombs that killed three people and wounded more than 180 others on April 15. Tamerlan Tsarnaev was killed in a police shootout, while Dzhokhar Tsarnaev was captured alive but badly wounded.

The amount of gunpowder that could be harvested from the kits — less than a pound and a half — would not have been enough to detonate the Boston bombs, company Vice President William Weimer said, although it’s possible some of that powder may have been used.

The absence of colored smoke in the Boston explosions and other special effects powders mixed in with the fireworks’ blast powder suggests the bombers sought and used an alternate fuel source, he said.

“My suspicion is they experimented with this, decided they couldn’t get enough powder out of them and went to look for another fuel,” Weimer said.

Fireworks are legal in New Hampshire, but not in Massachusetts.

Weimer said the company checked its records and found Tsarnaev’s name seconds after investigators released the suspect’s identity. FBI agents visited the Seabrook store Friday, interviewed staff and checked its computers. The FBI will not comment on whether investigators visited the store, agent David Couvertier said.

The store no longer has video of Tsarnaev’s visit in February because surveillance cameras record over the tape every 30 to 45 days.

Store computers don’t record an image of a customer’s driver’s license, but capture the information off it. The computer file on particular customers then reflects all purchases they have made. Tsarnaev’s only trip to the store was the cash transaction in early February, Weimer said.

“He was a one-store, one-time customer,” he said.

Weimer said it’s not his company’s first brush with terrorist activity. In 2010, the man accused of a failed Times Square car bombing was seen on surveillance video buying consumer-grade fireworks mostly made up of paper and cardboard from a Phantom Fireworks store in Matamoras, Pa.