There was a one-hour, 45-minute weather delay during the round and that eventually led to the suspension of play due to darkness. Due to the wet weather, lift-clean-and-place rules were in effect in the first round.
The first round will resume Friday at 8:00 a.m. (ET) with the second round starting on schedule at 7:05 a.m.
Those three top a crowded leaderboard that also has Kevin Johnson, Rich Barcelo, Geoffrey Sisk and Skip Kendall one stroke back at minus-6.
Nationwide Tour money-leader Michael Sim leads a group of five players tied for eighth at 5-under 66.
Gallagher did all of his damage in a 12-hole span on Thursday. He dropped in birdie efforts on the second and fourth, then moved to 3 under with a birdie at No. 7.
The 44-year-old ran off three consecutive birdies from the ninth to get within one of the lead. Gallagher posted his final birdie on the par-5 13th at TPC at Wakefield Plantation.
Gallagher is due for his third Nationwide Tour title. His first came in 1991 and his second in 2000.
Broadaway dropped in back-to-back birdie chances to open his round, then ran home his third birdie try on the fifth. He made the turn in 4 under thanks to a birdie on the par-3 seventh.
Around the turn, Broadaway collected three birdies in a four-hole stretch from the 11th to jump into the lead at minus-7. After stumbling to a bogey on the 17th, he closed with a birdie on the last to share the first-round lead.
'I got off to a quick start and made a lot of putts. It's really good to see them dropping,' said Broadaway. 'I've played well the last few weeks, but just haven't been making putts.'
Iles, who like Broadaway is looking for his first Nationwide Tour win, played the back nine first and carded a single birdie on the par-3 11th.
On the front nine, Iles poured in six birdies in a seven-hole span from the second to the eighth to jump into a share of the lead.
Sim shares eighth place at minus-5 with Chris Anderson, Chad Ginn, Tom Gillis and David Mathis.
Twelve more players are at minus-4, including Adam Bland, who is one of 19 players that has to complete their first rounds on Friday.