Josh Smith and Nick Coomes are not only graduates of Catholic High School, they also both attended the same elementary school.

“Me and Josh grew up together, practically,” Coomes said. “We lived the neighborhood over.”

The former St. Alphonsus Hornets are likely the first — or, at the very least, among a select few — former elementary school classmates to hit back-to-back home runs for LSU.

Coomes' and Smith’s homers jump-started a six-run second inning, which LSU used to cruise to a 10-4 win against Lamar on Tuesday at Alex Box Stadium.

Coomes, who hit 13 home runs for LSU-Eunice last season, gave LSU (26-12) the lead for good when he jumped on the first pitch he saw for a two-run homer to left-center field, scoring another former Catholic High teammate, Jordan Romero.

“We’ve been waiting for Coomes to show that power,” coach Paul Mainieri said. “We knew he had it.”

Smith was waiting at the plate to congratulate his long-time teammate. The three were part of a Catholic High state championship team in 2013 and jokingly continue a chant from that season to irk their teammates.

“We have a joke; any time we break it down, me, Josh and Jordan say, ‘State champs on one! One! State champs!’ ” Coomes said. “I came around and touched home, and those two are waiting for me. The first thing they said was, ‘State champs on one!’ ”

The first home run of Coomes’ LSU career gave the Tigers a 2-1 lead. Smith added to it right away.

Like Coomes, the freshman third baseman also turned on the first pitch he saw from Lamar starting pitcher Ryan Johnson (1-1), sending the ball a couple of rows deep into the right-field bleachers for his third home run of the season.

He said it hit him when he was rounding first base what had just happened.

"I told them when I got back (to the dugout), ‘That’s probably one of the coolest things we’ll do in our LSU career,’ ” Smith said.

Coomes and Smith started a barrage for LSU. Eight of the Tigers' 11 batters in the inning reached base. Five collected a hit, and six scored.

That big inning made a winner of sophomore right-hander Caleb Gilbert (2-1), who worked two innings in his first start since Feb. 21.

Things got off to a rough start for Gilbert. His first pitch of the game went over the left-field fence for a home run by Lamar right fielder Cutter McDowell, giving the Cardinals (22-16) a 1-0 lead.

Though Gilbert got through the rest of the first inning without giving up another run, he then had to deal with Mother Nature. The teams had to wait out a 1-hour, 8-minute delay in the bottom of the first inning, when rain forced the grounds crew to pull the tarp over the field and lightning in the area lengthened the delay.

Despite the long wait, Gilbert came back out to start the second inning, when he worked around a leadoff single to retire the side.

Lamar didn’t go down quietly after LSU’s big second inning.

McDowell — who had one home run in Lamar’s first 37 games — cracked his second home run of the game to lead off the top of the third against LSU freshman right-hander Matthew Beck to make it 6-2. He flew out to the warning track later in the game.

“That kid teed off on the first pitch of the game, then he hit another one and then he almost hit another one out on kind of a one-handed swing,” Mainieri said. “That kid has power.”

In the next inning, Cardinals third baseman Chad Fleischmann took Beck deep for a two-run homer to cut the LSU lead to 6-4.

Beck had only given up one earned run in his first 15 innings and had not given up a home run until Tuesday.

But the Tigers added a run on an Antoine Duplantis single in the fifth, then tacked on some insurance with a three-run seventh — two of the runs coming courtesy of a bases-loaded single by Greg Deichmann, who pushed his team-leading RBI total to 45.

Austin Bain, Nick Bush, Zack Hess and Hunter Newman combined to allow one hit in 5.1 combined innings of relief.

“Once Bain came in, he kind of stemmed the tide, and then the guys after him did a great job,” Mainieri said.

Follow Luke Johnson on Twitter, @ByLukeJohnson.