A house fire that injured five people in the Flatlands neighborhood of Brooklyn broke out in a home on East 38th Street early Wednesday morning.

Fire officials say their work was made more difficult due to the weather, with two nearby fire hydrants frozen, so they had to transport water to fight the blaze.

Officials also announced Wednesday a fire that broke out Jan. 17 on Staten Island — during which a two-year-old boy was rescued from a basement window — was caused by a space heater that was plugged in using an extension cord.

Space heaters are the biggest threat to safety amid dangerously cold temperatures, fire officials said.

“We need your help,” Fire Commissioner Robert Tucker said. “We need you not to leave a space heater on when you’re not in the room.”

Amid the recent extreme temperatures, fire officials reminded New Yorkers how to stay safe, saying to keep several things in mind regarding appliances:

• Always plug a space heater into the wall; never use an extension cord
• Keep space heaters away from doors and windows
• A 3-foot radius around the space heater should always be kept clear
• Try to buy a space heater with a thermostat and an automatic shutoff in case it tips over

“Once you go to sleep, you should turn off and unplug a space heater,” Kevin Woods, the FDNY’s Chief of Fire Operations, said. “It should not be running all night long while you’re sleeping.”

Woods also cautioned against using ovens, stoves, or dryers as alternate means of heating.

“Those appliances are not made to run for that amount of time. What’s going to happen is eventually it’s going to start to build up carbon monoxide in your home, which we know is a deadly gas,” he said.

Woods also said make sure your home has working smoke alarms and carbon monoxide detectors.

Another reminder was issued to New Yorkers saying not to park within 15 feet of a fire hydrant, so trucks are able to access water.