(CNN) One man and four children are dead after a standoff of more than 20 hours, Orlando police Chief John Mina said.

Mina said officers were in contact with Gary Lindsey Jr., directly and indirectly, by phone throughout the day Monday after he shot an officer around 11:45 p.m. Sunday and barricaded himself in an apartment with the four children, ages 1, 6, 10 and 11.

They had gone to the apartment in response to a domestic violence call from Lindsey's girlfriend.

At one point, Mina said, officers tried to give Lindsey another phone because his WiFi phone had a bad connection, and during the exchange they saw that one of the children was dead.

Orlando police Chief John Mina arrives for a news conference during Monday's hostage standoff.

Officers entered the apartment around 9 p.m. Monday, Mina said, and found the children dead of gunshot wounds in two bedrooms. Lindsey's body was found in a closet with an apparent self-inflicted gunshot wound, police said.

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