wms - How to get getGetFeatureInfoUrl from multiple layers in OpenLayers 3

I have multiple layers in a map with layer group now onclick I want to get the getGetFeatureInfoUrl for the different layers on which I am clicking but the problem is that I am getting only the Info for the last layer appended not the others.

Here is my code:

 var wms_layer;
    var map = new ol.Map({
        target: 'map',
        layers: [
        new ol.layer.Group({
            'title': 'Base maps',
            layers: [
            new ol.layer.Tile({
                title: 'Water color',
                type: 'base',

                visible: false,
                source: new ol.source.Stamen({
                    layer: 'watercolor'
                })
            }),
            new ol.layer.Tile({
                title: 'OSM',
                type: 'base',
                visible: true,
                source: new ol.source.OSM({

                    attributions: [
                    'All maps © OpenCycleMap',
                    ol.source.OSM.ATTRIBUTION
                    ],
                    url: 'https://{a-c}.tile.thunderforest.com/cycle/{z}/{x}/{y}.png'
                })
            })
            ]
        }),
        new ol.layer.Group({

            title: 'Hisar Data Layers',
            layers: [
            new ol.layer.Tile({
                title: 'Habitations',
                source: new ol.source.TileWMS({
                    url: 'http://192.168.2.2:8080/geoserver/HissarFullData/wms?service',
                    params: {
                        'LAYERS': 'HissarFullData:habitations',
                        'VERSION': '1.1.0',
                        'FORMAT': 'image/png',

                    },
                    serverType: 'geoserver'
                })
            }),
           wms_layer = new ol.layer.Tile({
                title: 'Hisar PWD',
                source: new ol.source.TileWMS({
                    url: 'http://192.168.2.2:8080/geoserver/HissarFullData/wms?service',
                    params: {
                        'LAYERS': 'HissarFullData:pwd',

                        'VERSION': '1.1.0',
                        'FORMAT': 'image/png',
                    },
                    serverType: 'geoserver'
                })
            }),
            new ol.layer.Tile({
                title: 'Hisar Block',
                source: new ol.source.TileWMS({
                    url: 'http://192.168.2.2:8080/geoserver/HissarFullData/wms?service',

                    params: {
                        'LAYERS': 'HissarFullData:block_boundary',
                        'VERSION': '1.1.0',
                        'FORMAT': 'image/png',
                    },
                    serverType: 'geoserver'
                })
            })
            ]
        })

        ],
        view: new ol.View({
            center: ol.proj.transform([75.7217, 29.1492], 'EPSG:4326', 'EPSG:3857'),
            zoom: 10,
            minZoom: 5,
            maxZoom: 17
        })
    });
    var layerSwitcher = new ol.control.LayerSwitcher({
        tipLabel: 'Layers' // Optional label for button

    });
    map.addControl(layerSwitcher);
    var viewProjection = map.getView().getProjection();
    var viewResolution = map.getView().getResolution();
    map.on('click', function (evt) {
        var url = wms_layer.getSource().getGetFeatureInfoUrl(
            evt.coordinate, viewResolution, viewProjection,
            {
                'INFO_FORMAT': 'text/html',
            });

        if (url) {
            document.getElementById('info').innerHTML =
            '';
            $('#myModal').modal('show');
        }
    });

Whenever I click on the map I always getting info of the HissarFullData:block_boundary layer. I am using Layer switcher with this .