Power outages hit almost 4,000 customers in Nassau late Monday afternoon after two electrical problems occurred around the same time, authorities said.

A mylar balloon got entangled in a transformer in West Hempstead, causing it to blow, while separately, power lines in Franklin Square came down, said spokeswoman Elizabeth Flagler for PSEG Long Island.

By about 7 p.m., 319 customers in Hempstead Town remained without power, with service expected back by 10 p.m. for most areas, according to PSEG Long Island's website.

Nassau police said the malfunctions, which happened about 5 p.m., left traffic lights without power, and officers were dispatched to direct traffic.

Customers affected by the West Hempstead outage began getting power back about 6 p.m., Flager said.

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The downed wires in Franklin Square were tied into two power circuits serving several communities, including in North Hempstead, and crews were making repairs, the spokeswoman said.

Extra personnel were dispatched to determine why the wires fell, she said.

At the height of the outages, about 3,800 customers had no power, according to the utility's website. That included more than 2,200 in Hempstead Town and almost 1,600 in the Floral Park and New Hyde Park communities in North Hempstead Town.