Police and military were conducting parallel investigations Wednesday on a shootout between their forces that left two policemen and one marine dead in a southern Philippine city.

Sr. Supt. Angelito Casimiro, Zamboanga City police director, told Anadolu Agency Wednesday that members of Regional Public Safety Battalion-9 and the Marine Battalion Landing Team-9 engaged in a firefight at around 7.30 p.m. (2330GMT) the pervious night over a still unconfirmed cause.

In addition to the deaths, a civilian duck egg vendor was wounded in the crossfire in Labuan village, located some 36 kilometers (22 miles) from downtown Zamboanga.

Confirming that investigations are being conducted by the military’s Joint Task Force Zambasulta and the City Police Office's Special Investigation Unit, Casimiro would not disclose the circumstances behind the incident.

However, a military source told Anadolu Agency on condition of anonymity as he was not authorized to speak to media that the police officers had first opened fire on the marines, killing one. He claimed that the marines returned fire, resulting in two casualties among the police.

He added that the marines had complained to police officials about their counterpart's alleged laziness and laxity, which may have prompted the confrontation.

The police and the marine units are both deployed in Labuan to cooperate in securing the village from kidnappers.

Last year, three people -- two teachers and a businesswoman -- were abducted in separate incidents in Labuan.

Army Col. Andrelino Colina, Task Force Zamboanga commander, told Anadolu Agency that the initial information he gathered suggested that the marines and personnel from Police Station 10 had been on patrol when the two regional battalion officers confronted them, leading to a shootout.

Western Mindanao Police Director Chief Supt. Miguel Antonio has ordered the police unit to pull out of Labuan to defuse the tension.

According to Casimiro, the regional police battalion has been replaced by SWAT personnel.

Security in Zamboanga City has been tightened since a faction of the Moro National Liberation Front (MNLF) Muslim rebel group laid siege to the area in September 2013.

The crisis, which last more than two weeks, left more than 300 policemen, soldiers and civilians dead and thousands of residents from six villages displaced.

Under the post-siege security setup, marines and army troops as well as air force foot soldiers and navy personnel help police secure the city’s 98 villages.