An unexploded bottle rocket was found near a grass fire that burned late Tuesday and early Wednesday and Boise Fire Department Battalion Chief Dave Cooper said fireworks are the suspected cause of the fire.

"It's difficult to prove that fireworks caused a fire unless somebody admits it," Cooper said Wednesday afternoon. He said a crowd of people was on Table Rock when firefighters arrived, but none said they could connect the blaze to fireworks.

Firefighters were stationed at the top of the Boulder Heights subdivision on Warm Springs Mesa. Four brush rigs and three engines were dispatched to the fire.

The fire was reported about 11 p.m. near the Table Rock quarry and was contained by 12:17 a.m. Wednesday. Cooper said a crew remained on the scene until about noon to keep an eye out for any hot spots.

As of about 3 p.m., the day had been largely quiet, excepting a tree fire Downtown, Cooper said.

Temperatures didn't reach 80 degrees until shortly before 2 p.m. The National Weather Service predicts a high of 88 for the holiday, which equals the city's average high temperature for July 4. The record high was 106 in 1937.